cmM 

Microfiche 

Series 

(Monographs) 


ICMH 

Collection  de 
microfiches 
(monographies) 


Canadian  Institute  for  Historical  Microreproductions  /  Institut  c-nadien  de  microreproductions  historiques 


I 


Technical  and  Bibliographic  Notes  /  Notes  techniques  et  bibliographiques 


The  Institute  has  attempted  to  obtain  the  best  original 
copy  available  for  filming.  Features  of  this  copy  which 
may  be  bibliographically  unique,  which  may  alter  any  of 
the  images  in  the  reproduction,  or  which  may 
significantly  change  the  usual  method  of  filming  are 
checked  below. 


n 


Coloured  covers  / 
Couverlure  de  couleur 


□    Covers  damaged  / 
Couverture  endommag^e 

□    Covers  restored  and/or  laminated  / 
Couverture  restauree  et/ou  pellicuiee 

I I    Cover  title  missing  /  Le  titre  de  couverture  manque 

I I    Coloured  maps  /  Carles  gecgraphiques  en  couleur 

□    Coloured  ink  (i.e.  other  than  blue  or  black)  / 
Encre  tie  couleur  (i.e.  autre  que  bleue  ou  noire) 

□    Coloured  plates  and/or  illustrations  / 
Planches  et/ou  illustrations  en  couleur 

I      I    Bound  with  other  material  / 


Relie  avec  d'autres  documents 

Only  edition  available  / 
Seule  edition  disponible 

Tight  binding  may  cause  shadows  or  distortion  along 
interior  margin  /  La  reliure  serree  peut  causer  de 
I'ombre  ou  de  la  distorsion  le  long  de  la  marge 
interieure. 

Blank  leaves  added  during  restorations  may  appear 
within  the  text.  Whenever  possible,  these  have  been 
omitted  from  fil.ming  /  II  se  peut  que  certaines  pages 
blanches  ajoutees  lors  d'une  restauration 
apparaissent  dans  le  texte,  mais,  lorsque  cela  elait 
possible,  ces  pages  n'ont  pas  ete  filmees. 


I       1    Additional  comments  / 

1 1    Commentaires  supplementaires: 


D 


L'Institut  a  micofilme  le  meilleur  exemplaire  qu'il  lui  a 
ete  possible  de  se  procurer.  Les  details  de  cet  exem- 
plaire qui  sont  peut-etre  uniques  du  point  de  vue  bibli- 
ographique,  qui  peuvent  modifier  une  image  reproduite, 
ou  qui  peuvent  exiger  une  modification  dans  la  metho- 
de  normale  de  filmage  sont  indiques  ci-dessous. 


D 
D 

n 


Coloured  pages  /  Pages  de  couleur 

Pages  damaged  /  Pages  endommagees 

Pages  restored  and/or  laminated  / 
Pages  restaurees  et/ou  pelliculees 

Pages  discoloured,  stained  or  foxed  / 
Pages  decolorees,  tachetees  ou  piquees 

j I    Pages  detached  /  Pages  detachees 

I .  •  I    Showthrough  /  Transparence 


n 


ion 


D 


Quality  of  pnnt  varies  / 
Qualite  inegale  de  i'impress 

Includes  suppler,  jntary  material  / 
Comprend  du  materiel  supplementaire 

Pages  wholly  or  partially  obscured  by  errata  slips, 
tissues,  etc.,  have  been  refilmed  to  ensure  the  best 
possible  image  /  Les  pages  totalement  ou 
parliellement  obscurcies  par  un  feuillet  d'errata,  une 
pelure,  etc.,  ont  ete  filmees  a  nouveau  de  fagon  a 
obtenir  la  meilleure  image  possible. 

Opposing  pages  with  varying  colouration  or 
discolourations  are  filmed  tv/ice  to  ensure  the  best 
possible  image  /  Les  pages  s'opposant  ayant  des 
colorations  variables  ou  des  decolorations  sont 
filmees  deux  fois  afin  d'obtenir  la  meilleure  image 
possible. 


This  item  is  filmed  at  the  reduction  ratio  checked  below  / 


lOx 


14x 


18x 


12x 


16x 


20x 


22x 


26x 


30x 


24x 


J 


28x 


32x 


The  coQv  filmed  here  has  been  reproduced  thanks 
to  the  generosity  of: 

MacOdrum  Library 
Corlefon  University 

The  images  appearing  here  ars  the  best  quality 
possible  considering  the  condition  and  legibility 
of  the  original  copy  and  in  keeping  wwith  the 
filming  contract  specifications. 


Original  copies  in  printed  paper  covers  are  filmed 
beginning  with  the  front  cover  and  ending  on 
the  last  page  with  a  printed  or  illustrated  impres- 
sion, or  the  back  cover  when  appropriate.  All 
other  original  copies  are  filmed  beginning  on  the 
first  page  with  a  printed  or  illustrated  impres- 
sion, and  ending  on  the  last  page  with  a  printed 
or  illustrated  impression. 


The  last  recorded  framo  on  each  microfiche 
shall  contain  the  symbol  — ^  (meaning     CON- 
TINUED"), or  the  symbol  V  (meaning  "END") 
whichever  applies. 

Maps,  plates,  charts,  ?tc.,  may  be  filmed  at 
different  reduction  ratios.  Those  too  large  to  be 
entirely  included  in  one  exposure  are  filmed 
beginning  in  the  upper  left  hand  corner,  left  to 
right  and  top  to  bonom,  as  many  frames  as 
required    The  following  diagrams  illustrate  the 
method: 


L  exemplaire  film6  fut  reproduit  grace  A  la 
g6n6rosit6  rie: 

MacOdrum  Library 
Carleton  University 

Las  images  suivantes  ont  dtd  reproduites  avec  le 
plus  grand  soin,  compte  tenu  de  la  condition  et 
de  la  nettetd  de  I'exemplaire  filmd.  et  en 
conformity  avec  les  conditions  du  contrat  de 
filmage. 

Les  exemplaires  originaux  dont  la  couverture  en 
papier  est  imprim^e  sont  film6s  en  commencant 
par  le  premier  plat  et  en  terminant  soit  par  la 
dernidre  page  qui  comporte  une  empreinte 
d'impression  ou  d'illustration,  soit  par  le  second 
plat,  selon  le  cas.  Tous  les  autres  exemplaires 
originaux  sont  film6s  en  commencant  par  la 
premidre  page  qui  comporte  une  empreinte 
d  impression  ou  d'illustration  et  en  terminant  par 
la  dernidre  page  qui  comporte  une  telle 
empreinte. 

Un  des  symboles  suivants  apparaitra  sur  la 
dermdre  image  de  chaque  microfiche,  selon  le 
cas:  le  symbole  — ^  signifie  "A  SUIVRE "    le 
symbole  V  signifie     FIN". 

Las  cartes,  planches,  tableaux,  etc..  peuvent  atre 
filmds  d  des  taux  da  reduction  diff^rents 
Lorsque  le  document  est  trop  grand  pour  etre 
reproduit  en  un  seui  cliche,  il  est  film6  d  partir 
de  I  angle  supdrieur  gauche,  de  gauche  ^  droite 
et  de  haut  en  bas.  en  prenant  le  nombre 
d'images  ndcessaire.  Les  diagrammes  suivants 
illustrent  la  m^thode. 


1 


MICROCOPY    RESOLUTION    TEST    CHART 

ANSI  and  ISO  TEST  CHART   No    1 


1.0 


I.I 


1^ 

ill:  3  2 


II  2.5 

[2.2 

2.0 
1.8 


1.25 


1.4 


1.6 


^     APPLIED   IIVMGE     Inc 


STUDIES  IN 
ANIMAL    BKHAVIOR 


S.  J.   HOI.M  hS,   I'h.l). 

ASSO(  lATt  rHi»FL.S.S(iK  o|'  /riiiLiH.Y,  LNUlkSITY  nK  i   \l.lt"KNr,\ 


BOSTON:     RICHARD     (1.    HADGKR 
TORONTO:    THE  COPP,  LLARR  CO.,  LlMITLl) 


CopYRiciir,  u)i(>,  nv  Rk  uaro  f;.  Hauokk 
All  Rights  Kubcrvi'd 


"4  5/ 


-Made  in  the  riiitcd  Statts  of  America 
The  Ciorb.un  Vtcss,  Boston,  U.  S.  A. 


i-iu.^-iu^u-i> 


i'Ri;faci; 


'T^IIl!   prcsLtit  volunic  is  larjioly  ilcvotcil  to  siih- 

-*•  jccts  with  which  the  writer's  own  investigations 

in  animal  hehaxior  ha\e  been  more  or  less  closelv 


conccrneii.      I  or  the  interest  of  th 


e  general  reailer 


cK 


the  special  contrilnitions  of  the  writer  ha\e  been 
made  siibon'jiate  to  the  broatier  aspects  of  these 
subjects.  Although  there  is  little  relationship  be- 
tween  the   various   topics   tleait   with,    the   tlifterent 


:hapt 


ers  are  not  (ie\oi(.l  ot   a   certai 


n  uni 


Th 


c  se\eral  types  o 


)f  beh 


nior  here  descn 


ty  of 
bed 


aim. 
were 


studied  in  the  endeaxor  t( 


)  get  a  fuller  insight  into 


r  mechanism,  or  to  interpret  them  from  the  ge- 


thei 

nctic  point  of  view.  These  two  methods  of  attack, 
are  not  opposed  or  mutually  exclusive,  as  is  some- 
times implied,  but  complementary.  We  cannot  ob- 
tain a  complete  explanation  of  behavior  by  an  analy- 
sis of  the  activities  of  the  indiviiiual  alone;  it  is  iicc- 
essary  to  know  also  the  evolutionary  history  of  the 
species,  and  the  various  steps  by  which  its  present 
behaxior  has  been  accjuiretl. 

The  first  chapter  is  historical  and  will,  it  is  hoped, 


prepare  the  reader  for  a  better  a 


pprcciation  of  the 


genera]  aim  antl  import  of  what  follows.     Some  of 


the  chapters  in  this  volume  ha 


ve  appearetl  elsewhere 


ns  special  articles.     I  wish  to  thank  Dr.  J.  McK 


een 


4  l'nf,ue 

Catull  for  his  jjcncrous  piTmission  t..  republish 
chapter  VI  from  Siifmc,  atui  chapter  XIII  arid 
parts  of  chapter  XI  from  the  />op,ilar  Sanur 
Monthly.  The  Wisconsin  Society  of  Natural  His- 
tory has  very  kindly  allowed  me  to  republish  chapter 
III  which  originally  appeared  in  the  bulletin  of  that 
society  for  June,  1912. 


COM  IMS 


rinprt » 

I.       AmMM      l*s\t  llol  !>(,>  ,    Till:    Oil)    AM)     Mil 
NlW  ...... 

II.      I'm    I  \()i.i  iiDN  or   l'\Ri\i\i,  C \R\   . 

Ill-      I'lii     Tkoi'isms    wi)   Tiimr    Riimids     h 
.Mori,  C'ompi  i  \   Modis  op  Hkiiwiok 

l\  .       Ihi    I'rohm  \i  mi    Oriint  \T|o\   . 

\.         Till      RiA  I  RSAI.    OF   TroI'ISMS 

\'I.  "^"iii   HMiiwiNcs  or  I\  ri:i.i,i(;i,\ci 
I 

\  II.     SoMi:  C'oNsiDi  RATIONS  o\  Till;   I'roiu.im  o 

Li  ARM\(i  ..... 

\'ni.  Till.  Imi'I.k  \iio\s  oiTri  \i,   \M)  Krror 

IX.  HlllWioR    \M)    Form   .... 

X.  Till    HiHwioR  oi-  C'l  IIS  . 

-Xl.  Till:  l\sn\er  OF  l*'ii(.\i\(;  Divm     . 

-XII.      Tin:    RiC'KiMTION    OF    Se.x    . 

XIII.       Thi.     Kol.l     OF    Sf.V     IN     TIM:    KvoiL  ITON     OF 
MiM) 

XIV'. .^^'ui;  Mind  of  a  Monkfv  . 

I.NDF.X 


s<> 

1 20 

1 39 

166 
'77 
>')7 
2ig 

230 

245 
263 


^' 


SII'DIIS   IN    WIMAl.   Hlliwio 


K 


STUDIES   IN  ANIMAL 
BEHAVIOR 


ANIMAL   PSVniOI.OCY,    VUV.  OLD  AND  TIIR   NE 


W 


pS'i  CH()[.(X;V  is  a  science  that  has  had  few  his- 
tonans.  and  the  special  province  of  animal  psy- 
chology has  never  been  accorded  the  dignity  of  a 
full   and  thorough  historical  treatment.      It  is   far 
from  the  intention  of  the  present  writer  to  take  up 
this  neglected  task.     But  there  are  a  few  salient  fea- 
tures of  the  development  of  this  branch  of  the  sci- 
ence which  ,t  may  be  desirable  to  consider  briefly 
in  order  to  prepare  us  for  an  appreciation  of  the 
aims  and  methods  of  present-day  animal  psychology^ 
1  he  animal  mind  has  enlisted  a  certain  amount  of 
interest  trom  the  earliest  times.     Do  animals  have 
souls?     If  so,  Do  these  souls  continue  to  live  after 
death.      How  do  the  souls  of  animals  differ  from 
the  souls  of  men?     Do  animals  reason?— these  are 
some  of  the  questions  which   exercised  the  earliest 
philosophers,   and  they  have  been   asked   more   or 
less  persistently  down  to  the  present  time.      Among 


lO 


SlKilii's   ill  .liiiiiuil   Biliiiiiot 


comparative  psycholofijists  these  questions,  except 
perhaps  the  last,  are  no  Ioniser  in  the  foreground  of 
interest.  l*rofessor  John  Dewey  has  reniarkeil  that 
in  philosophy  we  ilo  not  soke  our  [irolileiiis ;  we 
^et  over  them.  Ami  these  old  ([uestions  about  the 
animal  mind  that  ha\e  so  \niv^  perfilexed  erujuirinjr 
spirits  we  have  now  gotten  o\er,  ratlier  than  soKed, 
and  left  behind  in  onler  to  turn  our  attention  to 
more   fruitful  subjects  ot    iin  estimation. 

Modern  psychology  troubles  itself  \ery  little 
about  the  soul  as  an  object  of  encjuiry,  ami  animal 
psychology  concerns  itselt  with  this  subject  still  less. 
There  are  a  number  ot  (juestions  about  conscious- 
ness Vvhich  still  occupy  us.  Where  ilid  consciousness 
begin  in  the  course  of  ex'olution.  it  it  can  be  said  to 
have  had  a  beiriiinin;^;  at  all."*  liow  is  consciousness 
related  to  thi;  boiiily  structure  of  the  organism.-' 
What  arc  the  criteria  by  which  its  presence  in  an 
organism  may  be  recognized?  I  low  does  it  intlu- 
ence  behavior,  if  we  grant  that  it  can  influence  be- 
ha\ior? — these  and  many  other  rclatcil  problems 
continue  to  perplex  the  sclentilic  worker  aiul  the 
metaphysician  alike.  But  many  of  the  problems  are 
beginning  to  recede  from  the  foregrounil  of  inter- 
est, and  to  a  considerable  extent  we  may  get  o\er 
tiiem  in  the  future  and  leave  them  to  one  side,  al- 
though at  some  time  we  may  recur  to  them  with  re- 
newed msight  and  find  that  they  wear  a  ijuite  ilif- 
ferent  aspect. 

I'',\en    artiong   the   ancient   (i reeks    we    lind   much 


./;// 


//   r.^\,lio/,,t/y,   tlh-   Old  ami  the   .V,-tc- 


1 1 


tlic  same  liivcrsity  of  (.pinion  in  rcfrard  to  the  nicn- 
ral    life    of   animals    that   occurs   in    modern    times. 
While  it  was  contended  by  some  that  the  animals 
occupy  a  iK.sitioii  iinmeasurahlv  below  that  of  man. 
the  (.reeks  in  general  were  imlineil  to  a  more  gener- 
ous estimate  of  the  aiuinal  mind.     Apparently  there 
were    no    sustained    studies    of    aiiimal    psycholojry 
■Auunv^  the  ancient  (ireeks.  with  the  single  possible 
e\cepti(.n  of  tlic  o!.ser\  ations  of  Aristotle,  most  of 
which,    Iio\vc\  cr.    were    of    a    desultory    character. 
Aristotle's    three    treatises    on    /o'.logy '  contain    nu- 
■ncrous   records  of  tlie   habits   .,f  animals,   and   his 
^^eneral   estimate  of  the   mental   powers  of  animals 
nii-ht  well  pass  for  that  of  a  conservative  psycholo- 
m-t  (.t  the  present  time.  ]  Most  animals,  according 
to  Aristotle,  "appear  to  exhibit  gentleness  or  feroc- 
ity, mildness  or  cruelty,  courage  oi^ cowardice,  fear 
or  boldness,  violence  or  cunning;  and  manv  of  them 
exhibit  something  like   a   rational  consciousness,|  as 
wc  remarked  in  speakinjr  „f  their  parts.      For  they 
diit   r  tn.m  man.  and  man  from  animals,  in  a  greater 
'•r  less  degree:  for  some  of  these  traits  are  exhibited 
strongly  in  man,  and  others  in  animals."     The  ani- 
'"al   mind    corresponds   to   the   undeveloped   human 
nund,  for  in  speaking  of  infants  Aristotle  remarks 
nor  does  their  soul  at  this  period  differ  in  any  re- 
spect  trom   that   of  an   animal."      ("Hist    of    Ani 
mals,"    Hk.    S.) 

The   sage   observation   that  the   life   (.f  animals 
"■nay    be    divided    into   two    acts,    procreation    and 


12 


Sludies  in  Animal  Bchaiior 


feeding,  for  in  these  two  acts  all  their  interests  and 
life  concentrate,"  recalls  the  aphorism  of  Schiller 
that  hunger  and  love  are  the  ruling  forces  of  the 
world.  Aristotle  was  very  far  from  regarding  be- 
havior as  determined  by  external  stimulation.  He 
had  no  conception  of  reHex  action,  no  knowledge  of 
the  function  of  nerves,  and  he  rcgartled  the  brain  as 
an  organ  to  tem[KT  the  heat  of  the  heart,  the  lat- 
ter being  considered  as  the  seat  of  sensation. 

The  doctrine  that  animals  reason  found  an  ardent 
defender  in  Plutarch,  who  devotes  two  rather  curious 
chapters  of  his  "Morals"  to  a  consideration  of  the 
mental  powers  of  animals  and  their  relation  to  the 
faculties  of  men.  Diiierent  views  are  put  forward 
in  dialogue  form  much  after  the  fashion  of  Plato. 
The  discussions  are  of  interest  mainly  as  present- 
ing the  views  of  animal  intelligence  current  in  Plu- 
tarch's time.  Porphyry's  views  of  animals  were 
much  like  those  of  Plutarch,  although  they  were 
interwoven  with  his  Xeo-Platonist  doctrines  concern- 
ing the  nature  of  the  soul. 

The  Romans,  like  the  Greeks,  were  generally  in- 
clined to  give  credit  to  the  lower  animals  for  a 
considerable  amount  of  intelligence.  Pliny  with  his 
usual  uncritical  judgment  related  many  stories  of 
wonderful  animal  sagacity,  and  Celsus  contended 
for  the  essential  similarity  of  mind  in  brute  and  man. 
Galen  shows  an  approach  to  the  conception  of  in- 
stinct as  it  came  to  be  understood  by  later  writers. 
He  dwelt  at  length  on  the  adaptations  of  the  struc- 


.////;//.//  Psychnloyy,   ///<•    Old  and  the   Nciv        \T, 

turcs  of  animals  to  the  uses  to  which  they  arc  put. 
and  upon  the  inborn  proclivities  of  animals'  for  using 
their  parts   in   the   proper  way.     Just   as  the   muse 
mcites  the  poet,  so  do   the  innate  impulses  of  ani- 
mals lead  them,  without  instruction,  to  perform  the 
acts  needful  for  their  life.     Similar  views  were  ex- 
pressel  in  the  writings  of  Cicero,   (I),  \atma  Dc 
ont.    ,.     Seneca    wrote    in    much    the    same    vein: 
"What  practice   teaches   is  slowly   acquired   and   is 
made  after  many  patterns;  what  nature  teaches,  that 
IS  the  same  for  all,  and,  as  soon  as  there,  it  tal<cs 
place  w-ithout  reflection."     "Nature  teaches  nothing 
but  self-preservation   and  the  knowledge   necessary 
tor  this  end." 

During  the  Christian  era  there  were  few  recorded 
observations  or  speculations  on   animal  psychology 
before  the  Renaissance.   Interest  was  centered  mainly 
in  man,   and  especially  in  things   affecting  the  wel- 
fare of  his  soul,  and  most  of  the  attention  that  was 
bestowed  on  the  mental  life  of  animals  was  owing 
chiefly  to  the  bearing  of  the  subject  upon  theologi- 
cal teachings.     The  church  emphasized  the  inferior- 
ity  of   the    brute   creation    and   taught   that   it   was 
brought  into  existence  solely  for  the  service  of  man, 
although   this   doctrine  was   sometimes  qualified   by 
he  admission  that  certain  noxious  creatures  might 
have  been  produced  by  the  devil,  or  came  into  ex- 
istence as  a  consequence  of  the  Fall. 

The   conception    of    instinct   which    had    assumed 
more  or  less  dehnite  outlines  among  Roman  authors 


14 


Studit's  ill  Juimal  lieJuiviui 


came  to  he  more  clearly  clefincd  by  the  theological 
writers  of  the  latter  part  of  the  Middle  A^cs.  Of 
these  St.  Thomas  Aijuiiias  stands  preeminent  as  an 
authority  on  the  animal  mind  as  upon  most  things 
else.  A(|uinas  makes  a  sharp  distinction  between  the 
sensitive  soul  (anima  sensitiva)  and  the  intellectual 
soul  (anima  intellectualis) ,  ascribing;  the  lormer  to 
brutes,  ami  the  latter  only  to  man.  Animal  and  man 
are  therefore  separateil  by  a  broad  and  impassable 
barrier.  Animals  ha\e  sensations,  sensory  memory, 
but  they  ha\e  no  reason  {Smnw.u  Thitilniju  a, 
LW'I  and  LXXXIIH),  mo  real  freeilom  ( /.  <•. 
CXIll),  no  responsibility.  "\o  activity  of  the  sen- 
sitive part  can  ha\  e  place  without  a  body.  Hut  in  the 
souls  of  ilumi)  animals  we  tiiul  no  activity  hijrher 
than  the  sensitive  part.  1  hat  animals  n-ither  under- 
stand nor  reason  is  apparent  from  this,  that  all  ani- 
mals of  the  same  sfiecies  behave  alike,  as  beinjj; 
moved  by  nature,  and  not  acting  on  any  principle  of 
art;  for  every  swallow  makes  its  nest  alike.  J  here- 
fore  there  is  no  activity  in  tlie  soul  in  dumb  animals 
that  can  possibly  go  on  without  a  body."  (/.  c. 
LXVI.) 

j  "Sense,"  he  says,  "is  found  in  all  animals,  but  ani- 
mals other  than  man  have  no  intellect;  which  is 
proved  by  this,  that  they  do  not  work,  like  intellec- 
tual agents,  in  diverse  and  opposite  ways,  but  just 
as  nature  moves  them  to  fixed  and  uniform  speciric 
activities."!  "Sense  is  cognizant  only  of  singulars, 
but   intellect   is   cognizant   of    universals.      Sensory 


.^immal  Psychology,   the   Old  and  the   Xru'        15 
knoulcdsc  extends  only  to  bodily  things,  hut  intellect 

t^h  ^ITr'^l  '■'  "''"^^  in-rporeal,  as  wisdom, 
'  '^'^  ;'"'[  '^''.  '•^■'•'^^'"'^^  '^^tueen  ohjects."  The  won^ 
;-■';'!  adaptneness  and  perfection  of  instinct  are 
"'^  ':'  I'e  ascr.hed,  ,n  any  measure,  to  the  animars 
-n  nm.ame,  hut  redound  to  the  credit  of  the  Cre- 

"'^-  ideas  of  A.jumas  on  animal  psychology,  like 
;;'^'-Y;n   so  nKu,y<>ther  subjects,   were  g^^^^^^^^^^ 

-■-'-d  '>y  the  teachings  of  Aristotle,  but  he  em- 

us^.d  much  nu.re  than  his  n.aster  did  the  differ- 

nucs  between  brute  and  funnan  intelligence.     Aris- 

•''Y-.tly  perplexed  his  foHowers  and  interprc- 
U.s  by  h,s  vague  and  so.newhat  vacillating  treat- 
ment of  the  relations  of  the  rational  soul  to  the  s'n- 
.--•   -^'1   and   to   the   body.      Hut  the   learned   S. 

'—  promptly  settles  these  problems  with  a  de- 
-cness  that  leaves  no  room  for  doubt  concerning 
sown  standpoint.     The  writings  of  A.uinas  served 

tatus  oi   the   animal   mind.      The   opinions   of  this 

'"    "^'  '"'^•^"  '.'i""'""  ^--'n  d-vn  to  the  present  time 
'1^  the  writings  of  Descartes  we  lind  animal  be^ 
--  .nterprcted,    tor  the  first  time,   in   term        f 

-    uncnons  ot  the  nervous  system.     Descartes  w 
o.  .,   a,   ,„,,,,^,,„.  ,,^  ^,^^  ^^^^^^^^^^^  ^^_^^^  ^ 

o      o      h    nervous  systen,  and  he  arrived  at  manv 

U  Z  TTT    "•"^■^'P^--  "'■  ---c  physiologv. 

n.s  celebrated  doctrine  that  animals  are  a   toma^. 


i6 


Siiulii^   in   .1)11)11  (il   liilii)i'!<ir 


that  tlu'ir  activities  arc  entirely  iletennineil  by  their 
hotiily  orjraiii/ation  witlmut  knowleil^e  or  will  of 
their  own,  was  simply  the  result  ol  earryiiijj;  out  to 
its  lull  logical  eonse(|.ieiues  the  ineehaiiistic  physi- 
olojfy  that  he  hail  ailopteil.  "I  ha\e  dilij^cntly  eii- 
(]iiirecl,"  he  says,  '"whether  all  the  motions  ol  ani- 
mals came  I  rom  two  principle^,  or  only  from  one; 
ami  as  1  liml  it  clear  that  they  arise  from  that  prin- 
ciple alone  which  is  corporeal  aiul  meclianical,  I  can 
by  no  means  allow  them  to  ha\e  a  thinking  soul. 
Nor  am  I  at  all  hinJereil  in  this  conclusion,  by  the 
cunning  ami  sagacity  ot  lo\es  ami  lio^^,  nor  In  those 
actions  iloiie  from  lust,  huntxer  or  tear;  lor  I  pro- 
fess to  be  able  easily  to  explain  all  these  things  by 
the  sole  conlormation  ol  their  limbs." 

.\lthough  Descartes  ex[)laineil  by  a  physical  mech- 
anism what  had  been  previously  ascribeii  to  the  sen- 
sitive soul,  his  conclusion  was  eiiually  acceptable  to 
most  of  the  dignitaries  of  the  church,  inasmuch  as 
it  preserx  eil  an  essential  distinction  between  the  brute 
creation  and  man.  In  fact  this  disposition  of  the 
animal  world  was  hailed  with  satisfaction  by  niany 
church  authorities,  anil  it  was  rapidly  followed  by 
various  writers  several  ol  whom  ile\  eloped  even 
more  extreme  views.  Malebranche,  for  instance, 
tells  us  that^Among  cats  and  dogs  ami  other  ani- 
mals there  is  no  intelligence,  no  spiritual  soul  as  we 
are  commonly  toUl.  I  hey  eat  without  pleasure,  cry 
without  pain.  I  hey  grow  without  knowing  it;  they 
ilesire  nothing;  the\    know  nothing,   and  il  they  act 


■  fximal  /\y.hn/.„j,,    ,lu-    ()l,l   ,„„i  //,,.    v^^^. 


'7 


^^'''-^"I'l'vss.  andin.  .nannc-r  that  imiuato  mtdli- 
«c.K..  ,t  ,s  lH..u,se  (..,J.  i„  u.akin^.  ,lK.,n  Inr  sdl- 
PrcscrvatH.n.  has  cnstitutcd  their  bodies  in  such  a 
-av    that    t  K.    uith.h-au-    nr^a.ncally    a.ui    w.th.n.t 

^    'un,,., ,.,,,,,      ,UKnuu,d.stn,y  then,  and  that 
tiU'v  sccni  to  I  tar.  V 

^'■^Y'';""''""*^"^''^'^'^^-^^^-a^i"^'vitahIc.     Thcv 
-Ku.-rc<l   the   ruiculc  of   [,a    lontainc,   the  protest 

•"    i-K-od  lather  Honjeant.uhoheheved  that  ani- 

'•>als    uere   inhabited   by   tl.e   souls  of  denu.ns,   and 

'-  er,t,us„,  of    rhon.asius,  Ciasscndi,  Leihnit       n 

an>^ot   ers.  of  who.  the  Trench  Inspector  of  iC- 

u    n^e  ■  7'7':"7*^^'^^  ^'  P-ifi""  -^  especial  prorn- 

c       I.eRoys   /.^///r.  ..r  /o    ./...,.,,  contain 

'■".-I'scrvations.M,  the  training  of  animals  and 

Hr  ,nd.cat.ons  of  nuelli.ence,  but  their  chief  dis- 

c    eature  .s  thur  attetnpt  to  explain  the  actions 

".•"-"ly  attributed  to  instinct  as  the  result  of  in- 

;he'^::lT:•■^^,•v•-^/----•-"'pHn 


same   chrection   is   found   in   Erasmus    Daruin's 


the 

f::^""'"-.     '^^"■"'"    ^'--^    ^'^at    the    markc^i'^e: 

"/"'''""■'■  ;"  ^''^'  ^"••"'  --1  ^'-Krions  of  the  bodies 

"  '"";  ^'"^'  — ^''^  ^-''-^'1^1  load  us  to  expect  a  sirni 

lar  endoun.ent  of  sensations,  etnotions  L.\  me  tal 

!:z7:r'^  '^^-i-vorstoshowth::';;::! 

'f^'al   acts  of    anunals   are  learned   like  tnost  of 

'  own,  and  that  certain  habits  appear  innate  sim- 

>  l^ccause  u-e  do  not  attend  with  sufHcient  care  to 

^h.  early  sta.^es  of  their  formation.    The  chick  w  Iks 

-un  after  natch.ng,  but  before   this  titne  it  ,  ^. 


18 


Siii(li<^    in    ./niitiiil   Ri'lidvior 


its  fett  ;il>Mur  while  in  tlic  shell,  it  pciks  at  t(t(ul, 
hut  lu-t'orc  this  it  npciis  ami  shuts  its  iimuth  and  swal- 
lows sonu'  of  the  white.  'I'he  ahility  of  calves  anil 
eolts  to  \\;ilk  soon  alter  hirth  is  attrihuted  to  their 
stru^Liles  while  still  in  the  uterus.  l'.\en  the  human 
t'a'tus  ^uiks  in  ainiiiotie  lluid  ami  |'learns  to  swallow 
in  the  same  manner  as  we  learn  all  other  animal  ac- 
tions whieh  are  attetuled  with  consciouwicss,  hy  the 
repeated  eltorts  of  our  muscles  under  the  control  of 
our  sensations  and  volitions. 'l 

iJreathinir,  a  more  difficult  case,  is  accounted  for 
as  follows:  "The  inspiration  of  air  into  the  lunji;s 
is  so  totally  dilterent  from  that  of  swallowing  a 
fluid  in  which  we  are  immersed,  that  it  cannot  be 
acijuired  liefore  our  nativity.  But  at  this  time  when 
the  circulation  of  the  blood  is  no  lonj^er  continued 
throujrh  the  placenta,  that  suffocating  sensation  which 
we  feel  about  the  pra'cortlia  when  we  are  in  want  of 
fresh  air,  disagreeably  affects  the  infant  and  all  the 
muscles  of  the  bmly  are  excited  into  action  to  relieve 
this  oppression;  those  of  the  breast,  ribs  antl  dia- 
])hragm  are  fouiul  to  answer  this  purpose;  and  thus 
respiration  is  discoveretl;  and  it  is  continued  through- 
out our  li\  es  as  long  as  oppression  begins  to  occur." 
Darwin  is  not  daunted  c\en  by  the  clear  indications 
of  instinct  presenJcd  by  s  cial  insects,  for  he  says, 
"If  we  were  better  acquainted  with  the  histories  of 
those  insects  which  arc  forim  .1  Into  societies,  as  the 
bees,  wasps  and  ants,  I  make  r:i  doubt  but  wc  should 
fmd  that  their  arts  and  improvements  arc  not  so 


I 


^■luimal  Psychnhyy,   t/,,-  O/J  ami  the  Xcw        i.j 

siniilar  ami  unih.nn  as  they  n..u-  appear  t„  us.  but 
that  they  arose  in  th.  same  manner  ivnm  experience 
ami  tradition,  as  the  arts  ..f  our  own  species,  though 
their  reasoning  is  from  fewer  iJeas,  and  is  busied 
with  fewer  objects  and  is  exerted  with  less  eneriry  " 
Smnlar  views  were  developed  by  Condillac  in  his 
/  r,i,ir  tirs  Jnituaux  published  in  1766. 

What  had  come  largely  throujrh  the  writings  of 
Aquinas  and  his  followers  to  be  typical  catholic  doc- 
t'lnc  cnncermnK  the  mental  life  of  animals  found  a 
^cry  able  dcknder  in  S.  11.  Keimarus.  a  prominent 
prelate  ot  the  church,  but  at  the  same  time  an  indus- 
trious worker  in  the  field  of  animal  behavior.     His 
^u.t    work,    .llhjnncnu-    liitn„lu,nu,ni    „hn-    die 
Inrhr  Jrr    I  hurr,    remained    fur  a    lon^  time    tiie 
m-st  extensive  and  thorouirh  treatise  on  the  subject 
It  passed   thruuKh   four  German   editions  and   w^- 
translated   mt<,    J- rench    and   into    Dutch,   ..nd   so.,, 
came  to  be  re^rarded  as  a  standard  authority      The 
Mcws  ol  LcRoy,  Iirasmus  Darwin  and  Condillac  are 
subjected  to  a  rigorous  criticism  which  in  most  re- 
spects must  be  regarded  as  verv  well  founded.     The 
■'I'ors   of   Reaumur,    R<isel   von    Rcisenhof,    I  luber 
I  nnnet,  Hufion,  Spallan/ani  and  other  naturalists  of 
the   seventeenth    and   early   part   of  the   eighteenth 
cvntunes  had  added  greatly  to  our  knowledge  of  the 
-nstinctive  behavior  of  animals,  and  Reimarus,  from 
fns  wide  acquaintance  with  literature  and  fro-n  his 
"un  experience,  had  little  difficulty  in  making  out   i 
strong  case  for  instinct.     The  kev-note  of  (he  work 


20 


Siti(Jii<i   in   .liiiiUiil   lit  hill  lor 


is  cX[irc'ssril  in  tlii  title  (it  .m  i.:irlivr  trc.itisi-  I ii- 
slinilii^  hr/il'irnin  r  \;'v/,  ;/.n,»  l),i,  (  iii^i'iiii  ijin'  ^al'iiii- 
liyuini,  iniliiit)i,  issucij  In  172".  I  lu'  u  (iniKilii! 
ifistiruts  (if  animals  ianndt  Iv  c\[>Iainiil  iiri  the  basis 
of  ai()iiircHl  habits;  thcv  air  innate  ciulownicnts,  pc?'- 
fi-cfly  adapted  td  •eeiire  the  \'  elfare  of  the  iiniividiiai 
animal  or  its  progeny,  ami  heme  an  irrefray;ahle  tcs- 
tiniony  to  the  wisdom  and  beneficence  of  the  Crea- 
tor. Reirnariis  was  stronjfly  intlueneed  In  Aristotle 
anti  St.  I  homas  .\(]ninas.  I  le  is  at  j^reat  pains  to 
show  that  theri-  is  a  fiuulamental  ditterence  between 
instinct  and  reason,  ami  that  nian  alone  has  true 
ratif)nality.  i  le  concedes  to  the  animals  perceptions, 
memory,  volition  and  the  ability  to  lear?i:  but  he  de- 
nies that  they  ha\e  abstract  or  general  ideas  or  any 
power  ol  passinir  from  one  representation  to  an- 
other. Hy  numerous  other  writers  animal  instinct 
came  to  be  ilwelt  upon  as  aff()rdin(r  some  of  the 
most  conclusi\e  e\idence  of  design.  I'aley  ililates 
u[ion  it  at  lenjrth  in  his  .Witiinil  Tlhaloijy,  and  one 
ot  the  \(ilunies  ol  the  Briiljj;ewater  treatises  is  tie- 
voted  to  this  fruitful  topic. 

Throuj^diout  human  history  there  ha\c  been  sev- 
eral motixes  behind  the  \arious  di\er.ii;ent  opinions 
that  ha\e  been  held  in  ret^ard  to  animal  psveholojry. 
The  impulse  of  the  sympathetic  lo\er  of  animals  to 
attribute  to  his  dumb  friends  and  depindents  a  gen- 
erous meeil  of  intelligence  has  always  been  a  more 
or  less  potent  influence.  .Xml  then  there  is  the  temp- 
tation to  tell  a:,  remarkable  a  tale  as  possible  of  the 


IHrlunnaiKcs  ol"  tlu  rrcatmcs  dcsc  rihid.     Hotli  these 
taukfuics  frniucntly  k;ul  to  rciulin^j  Into  an  animal's 
;icti«ns  an  iinuarr.i.ital.k-  amount  of  sajracity.      Hut 
niorc-  powerful  than  fh.sc  motives,  especially  clurinK' 
the  C  hnstian  era.  ha\e  been  the  vari(,us  theological 
pivpossessi.Mis  ol  Jitte.ent  schools.     In  the  lyth  ami 
iSth  centuries  ue  me.f  uith  two  opposed  tendencies 
iM  the  interpretation  of  animal  behavior;  one  toward 
attnhutinjr  the  actions  of  anir.ials  to  the  same  facul- 
ties that  are  possessed  hy  human  hein^s  and  leading 
t"  ;•  limitation  of  the  sphere  of  instinct,  or  even  to 
dcnvMiK'  instinct  alto^r,ther;  the  other  toward  evplaiti- 
inu  animal  hehavi.r,  so  far  as  possible,  in  terms  of 
iMstmct  or  automatism,  with  the  limitation  of  reason 
and  all  higher  mental  attributes  to  man  alone.     The 
ph.los,.ph.cal  skeptics,   in   ^a-neral,   were   partial   to- 
ward the  first;  the  defenders  of  the  faith  towarti  the 
second.      I  he  one  class  of  writers  attempted  fo  link 
"'^':'  ^'.'1^1  ^"mnal  more  closely  tojrcther,  and  to  show 
t  Kir  fundamental  kinship;  the  other  tried  to  make 
the  ;,r;,p  between  man  ami  animal   as   wide  as  pos- 
Ml)le.  and  to  show  that  there  is  an  essential  differ- 
ence between  them.     "After  the  error  of  atheism  " 
says    Descartes,    "there    is   m.ne    which    leads   weJk 
nunds  further  from  the  path  of  virtue  than  the  idea 
Mat  the  minds  of  animals   resemble  our  own.   and 
tlicrefore  that  we  have  no  greater  right  to  a  future 
lite  tfian  have  gnats  and  ants,  while  on  the  contrary 
"ur  mmd  is  quite  independent  of  the  body,  and  does' 
not  necessarily  perish  with  it." 


22 


St  lull  cs  in  .In'imal  Behavior 


I  he  same  consiilcratinns  that  inspircil  this  utter- 
ance of  Descartes  still  have  weight  in  determininp; 
the  attitude  of  modern  students  toward  problems 
of  animal  hcha\ior.  In  the  conclusion  of  his  interesl- 
in|j;  book  on  the  Psydmlot/y  of  Jnls  and  of  llujlur 
.Inimals,  I'ather  Wasuiann,  one  of  the  foremost  in- 
vestigators of  the  behavior  of  social  insects,  writes  in 
regard  to  modern  e\olutionary  psychology  that  "By 
tienying  the  existence  of  the  essential  difference  be- 
tween animal  and  human  psychic  faculties  this  psy- 
chology noc  only  raises  brutc^  to  the  dignity  of  man, 
hut  degiades  man  to  the  le\  el  of  the  brute.  Woulil 
to  (lOil  that  this  were  done  in  theory  only;  hut  alas! 
the  practical  conse(]uence  of  this  false  theory  is  the 
den. .)ralization  and  brutali/ation  of  nian." 

i  here  Is  no  denying  the  serious  import  of  the 
problems  about  which  comparative  psychologists  do 
battle.  Hut  even  if  the  victory  should  fall  to  the 
most  materialistic  of  the  contending  parties  it  is 
harilly  to  be  expected  that  the  consequences  would 
be  as  dire  as  Wasnuuui  surmises.  We  are  bid  to 
beware  ot  the  same  old  scarecrow  that  has  so  often 
appeared  in  the  path  of  scientific  progress.  But  its 
aspect  is  growing  less  terrible  as  time  passes,  and  it 
is  always  the  part  of  the  man  of  science  to  go  straight 
ahead  as  if  it  were  not  in  existence. 

The  first  to  grapple  in  a  very  serious  way  with 
the  prolilcm  of  the  evolution  of  instinct  was  l-a- 
niarik.  although  we  meet  with  suggestions  in  regard 
to  the  inhc'-itance  of  the  cHects  of  habits  in  the  writ- 


Animal  Psychohujy,  the  Old  and  the  Nczv 


23 


i 

-i 


■A 

-55 

■3 


ifiRS   of  LcKoy.      I.aniarck   rejrarclc'd  the  evoluticm 
of  animals  as  brought  about,  to  a  very  large  extent, 
by  psychic  factors.     His  three  primary  divisions  of 
the  animal  kingdom,  the  apathetic,  the  sensitive  and 
the  intelligent  animals,  are  based  on  psychological 
distinctions.     'Ihe  apathetic  animals,  such  as  the  in- 
tusoria,  polyps,  etc.,   are,  like  plants,  irritable,  but 
dc\-oiii  of  consciousness  and  spontaneity.     The  tran- 
sition  from   the   apathetic   to   the   sensitive   animals 
comes   with   the   development  of   a   nervous  system 
which  was  erroneously  regarded  as  absent  in  some  of 
tlie  higher  members  of  the  apathetic  group.     Con- 
sciousness first  appears  in  a  vague  form,  but  as  or- 
g;ini/ation    advances    ana   the    nervous   system    and 
sense()rgans  become  more  specialized  and  perfected, 
consciousness   comes  to  assume  more  of   a   guiding 
role  in  the  process  of  evolution.     Everywhere  con- 
sciousness is  considered  by  Lamarck  as  dependent 
upon   the  organization  of  the  nervous  system,  but 
as  he  is  an  "interactionist"  he  regards  the  activities 
of  animals  as  initiated  to  a  large  extent  by  their  feel- 
ings and  desires. 

As  is  well  known.  Lamarck  explained  instinct  as 
inherited  habit;  but  habits  depend  upon  antecedent 
desires  of  the  animal;  these  lead  to  efforts  by  which 
the  desires  may  be  satisfied,  and  by  fre(|ucnt  repe- 
tition the  acts  thus  proiiipted  become  habitual  and 
a  a-  passed  on  as  inheriicd  proclivities  tc.  followifig 
generations. 

W  ith  the  appearance  of  wants  determination  of 


24 


Simlu'.^   in   .Inliiuil   Biliuiinr 


;ufi()ii  l)(.t()iiKs  j^railually  transferred  from  the  out- 
side ot  file  ()i-<^r;inlsm  to  the  inside.  \e\v  wants  en- 
gender new  haliits  and  jjji\e  rise  ti  lew  orj^ans.  In- 
stinct is  regarded  as  internal  impulsion  instead  of 
response  to  outer  stimuli.  It  stantis  sharply  marked 
oH  irom  the  activities,  however  coitiplex,  of  the 
lower  orj^anisms  whose  behavior  is  entirely  deter- 
minetl  by  their  environriient. 

With  the  advent  of  the  vertebrates  with  their  well- 
ilev  el()|)ed  brain  we  have  the  appearance  of  intelli- 
j^ence  and  free  will,  i.ariiarck  setlulously  avoids  the 
anthropomorphism  of  iv.:in\  previous  writers  in 
maintaininj^r  that  S-itelli^ence  and  will  can  arise  only 
in  higher  animal.-,  which  have  the  re(]uisite  nervous 
organization.  With  the  perfecting  of  this  organiza- 
tion the  higher  mental  faculties  become  further  de- 
\el()ped,  ami  reach  their  culmination  in  the  mind 
ot  man  which  is  regarded  as  the  outcome  of  a  con- 
tinuous process  of  evolution. 

Although  much  hail  been  written  on  the  instincts 
and  habits  of  animals  in  the  half-century  following 
I.amarck,  there  was  but  little  contributed  to  the  doc- 
trine ot  mental  evolution  until  we  come  to  Herbert 
Spencer,  who  untlouhtedly  ranks  as  one  of  the  great- 
est ot  all  genetic  psycholoirists.  Spencer's  Ptinciplcs 
I'l  Ps\,li>i!()i/y  was  pul)lisheil  in  iS^^,  but  several 
years  later  after  the  Darwinian  theory  had  been  pro- 
mulgnted  it  was  reissued  in  a  revised  and  consider- 
al^ly  .ill  irgcd  form.  I  lis  treatment  of  life  and  mind 
Irom  tile  common  Siandpoint  of  the  adjustment  of 


I 


Animal  Psychology,   the  Old  and  the  N 


czv 


t 
J 

■I 

-is 


internal  relations  to  external  relations,  his  derivation 
<.f  instinct  from  rerlcx  action,  his  filiation  of  the 
I'l-ocess  of  reasoninjr  with  perception,  his  attempt 
tn  show  that  no  sharp  distinction  can  he  drawn 
hetween  instinct  and  reason,  his  e!lort>  to  gi  e 
an  account  of  the  origin  of  the  intuitions  of  space 
and  time  and  the  fundamental  forms  of  thinking  in 
terms  of  experience  gradually  accumulated  throug.'i 
inheritance,  and  his  theories  of  the  genesis  of 
moral  impulses  and  a'sthetic  sentiments,  are  among 
•'ic  many  notahle  features  of  this  very  original  and 
c'osely  reasoned  hook. 

Spencer  was  a  heliever  in  the  transniission  of  ac- 
<liJired  characte,-s,  and  much  of  his  psychological 
s;K"cu!ation  is  hased  upon  this  doctrine.  '  Many  of 
hi::  cherished  deductions,  however  alily  wrought'out. 
will  have  to  he  discarded  if  the  etlects  of  experi- 
ence, as  so  many  biologists  now  heliexe.  are  not 
transmitted  to  the  following  generation.  But  if 
tlie  foundation  of  many  of  Spencer's  doctrines  were 
to  he  removetl,  tnuch  of  permanent  value  would 
nevertheless  remain  unshaken.  The  genetic  method 
m  the  study  of  psychology,  as  well  as^n  manv  other 
fields  of  thought,  owes  much  to  Spencer's  illuminat- 
ing thought  and  stimulating  influence. 

Only  four  years  elapsed  hetween  the  publication 
"t  Spencer's  /'.  v,7/o/,u/y  and  the  :ippearaiue  of 
Darwin's  Orujiu  „f  S/urir<.  The  latter  work 
marked  an  epoch  in  the  history  of  psychology  as  well 
as  of  biology.      Darwin's  theor\  of  natural  selection 


26 


Siudirs  in  Jtiimal  Behavior 


afforded  a  means  of  explaining  the  esolution  of  in- 
stincts, as  of  corporeal  structures,  by  the  slow- 
accumulation  of  favorable  variations.  In  the  chap- 
ter <jn  "Instinct"  in  the  Oriyin  of  Species,  Darwin 
showed  that  even  wonderful  and  complex  instincts 
such  as  those  of  the  hive  bee  did  not  present  in- 
superable difHcultics  to  his  theory.  Could  the  theory 
be  extended  to  explain  the  derivation  and  evcjlution 
of  intelligence  and  possibly  also  the  development  of 
the  human  mind  itself  from  that  of  lower  forms? 

In  the  Descent  of  Man  Darwin  attempts  to 
show  that  the  mind  of  man  is  fundamentally  the  same 
in  kind  as  that  of  the  animals,  and  differs  only  in  de- 
gree of  development.  He  attempts  to  show  that  the 
moral  sense  which  had  been  often  held  up  as  man's 
peculiar  possession  and  glory  is  an  outcome  of  the 
social  instincts  and  emotions  fount!  in  higher  ani- 
mals. Such  conclusions,  with  their  far-reaching  con- 
sequences, naturally  aroused  strong  opposition  on 
the  part  of  many  conser\  ati\e  people,  while  at  the 
same  time  they  aHf)rded  an  inspiring  outlook  to  Dar- 
win's followers.  Attempts  to  trace  the  genesis  of 
human  faculties  were  the  natural  outcome  of  the 
stimulus  which  Darwin  gave  to  the  study  of  compara- 
ti\  e  psychology,  just  as  attempts  to  trace  the  lines  of 
descent  of  various  groups  of  the  animal  kingdom 
followed  closely  upon  the  early  battles  over  the 
MUitability  of  species.  Romanes'  volumes  on  Jni- 
inal  Intelliyence,  Mental  Evolution  in  .Jninials  and 


?? 


-5 
f 


I 


.IiiiuKtl  Psyihology,   the   Old  <nid  the   Nczv 


27 


Mnildl  /■kn/iitinn  in  M tm  arc  amonj^  the  best-known 
products  of  this  nio\cnu'it. 

J  here   was  a   strong  teiuiency  toward   anthropo- 
morphism in  many  post-Darwininn  writers,  as  there 
was  in  several  of  the  skeptics  of  the  eighteenth  cen- 
lury.      The    effort   to    show   that   the    human   mind 
tvoKctI  from  the  animal  mind  led  many  to  read  an 
undue  amount  of  intelligence  into  the  activities  of 
animals.      The    works    of    Perty,    Biichner,    \'ogt, 
Urehm.  and  to  a  certain  extent  Romanes  afford  illus- 
trations of  this  failing.     What  Wasmann  calls  "hu- 
manizing the  brute"  became  a  favorite  theme.     Se\-- 
rral    writers   of    the    early    post-Darwinian    period 
restrained    within    reasonable   limits   whatever   bias 
tlicy  may  have  had  toward  anthropomorphism,  and 
contributed  observations  and  experiments  whicli  b.avc 
rlirown  much  light  on  the  problems  of  animal  psy- 
chology'.    Among  these  may  be  mentioned  Lubbock, 
I  ore!,  IJoyd  Morgan,  Dr.  and  Mrs.  Pcckham,  Mc- 
Cook  and  many  others.     Ihe  scholarly  works  of 
(.roos  on  The  Play  of  .huinals  and  The  Play  nf  Man 
are  excellent  examples  of  the  application  of  Darwin- 
ian principles  to  the  interpretation  of  behavior. 

Among  post-Darwinian  author  on  animal  psy- 
Hiology  there  soon  arose  a  division  between  the  nco- 
Darwinians  who  attributed  evolution  mainly  or 
solely  to  natural  selection,  and  the  nco-I,amarckians 
uho  attached  much  greater  importance  to  the  in- 
heritance of  the  effects  of  experience.    This  division 


J 


28 


Sinilils   in   .liiinuil  lirhiivior 


was  l(ii\sli;ul<i\\\j  hv  the  diltciMit  cktrrccs  of  im- 
portatuc  attacficil  hy  Darwin  ami  SpmcLr  to  the 
factors  of  natural  s.kttioii  ami  the  transmission  of 
ac(iiiirc-(l  characters.  Darwin  accepted  the  latter  the- 
ory, hut  assi(,nKHl  to  the  I.atnarckian  factor  a  suhor- 
dinate  role  as  compared  with  natural  selection.  Spen- 
cer, who  had  already  elahorateil  liis  system  of  psy- 
chology 0,1  the  hasis  of  the  l.amarckian  theory, 
iKiturally  attached  jr,-c:it  weight  to  that  doctrine,  hut 
when  the  theory  of  natural  selection  was  announced 
he  cortlially  receixed  it,  hut  he  appealed  to  it  mainly 
as  a  helpful  subsidiary  hypothesis. 

Since  Weismann  maile  his  attack  upon  the  l.a- 
marckian theory  he  has  been  followed  by  a  consider- 
able number  of  jisycholoirists.  such  as  Lloyd  Morjran, 
Forel,  Ciroos,  Whitman,  Baldwin  and  Zeigler,  who 
reject  entirely  tlie  doctrine  that  aci]uired  characters 
are  transmitted.  .\mon^r  the  neo-Lamarckians  who, 
thouj^^h  somewhat  in  the  minority,  still  represent  a 
tlourishinjT  school,  there  are  all  sorts  of  views  re- 
gardmjr  the  potency  of  natural  selection,  some  writ- 
ers t^^oino;  so  far  as  to  cast  the  theory  aside  as  a 
visionary  antl  ^n-oundless  speculation.  Romanes, 
I'.imer,  llaeckel,  I  lerin^,  Wundt,  Cope,  Semon  and 
I'auly  are  amoiifr  the  [irincipal  writers  of  this  school 
who  ha\e  concerned  themsehes  with  comparative 
psychology.  The  combination  of  vitalism  and  La- 
marckism  which  is  presented  in  the  writings  of  I'auly 
and  France  affords,  in  the  opinion  of  its  adherents, 
a   method   of   accounting   for   the    development   of 


.luimal  PsychnUnjy,  ihr  Old  ami  the  Nczv       29 

adaptations  quite  indcpcndcntiv  of  natural  selection 
'  (m  ,s  done  by  endowing  the  orKaniMU  with  a  teleo- 
l-Kica  principle  which  makes  all  the  adinstn.ents  re- 
Mi-red  to  meet  its  needs;  these  adjust.nents  are  then 
transmitted  to  the  descendants  and  thus  gradually 
cftect  a  progressive  adaptive  muditication  of  the 
s[)ecies. 

\Vithout  raising  the  ijucstion   as  to  whether   the 
Mtalistic  explanation   of  adaptation    reallv   explains 
anything.  ,t  might  he  remarked  that,  since  a  t.leo- 
i..gically  working  principle  is  assumed  as  the  basis 
f'T  the  aciu.red  adjustments  u\   the  individual    the 
same   principle   might  also   be   evoked   to  guide  the 
entire  course  ot  evolution  without  appealing  to  an 
agency  of  such  questionable  potency  as  the  I.amarck- 
■an    factor.      h„ha   nun   sunt    nudtipluanda   f>n„t.r 
"r.rssitatnn.      It   we   invoke   any   vitalistic  agencies 
or  teleological  principles  we  might  as  well  give  them 
plenty  to  do. 

The    the|,>ry    of    organic    evolution    having    been 
'■nnly    established,    and   the    conviction    having   be- 

"ne  (,uite  general  among  psychologists  that  the  hu- 
M.an  mind  has  resulted  by  a  continuous  process  of 
development  from  the  mind  of  animals,  the  contro- 
\ersial  mterest  in  various  questions  that  stimulated 
Mie  earlier  post-Darwinian  students  of  the  animal 
'""Hi   has  to   a   considerable  extent  subsided.      The 

't-rt  to  trace  the  evolution  of  particular  instincts 
and  mental  faculties  continues  to  attord  an  absorbing 
and  fruitful  occupation,  but  such  work  is  pursued 


30 


StiiJits  in  .Jiiinuil  livhav'uir 


not  so  much  with  the  aim  of  establishing  the  fact  of 
cxohition  in  a  particular  field,  as  of  illuminatinjj; 
the  suliject  in  the  lif^ht  of  its  historical  development. 
In  human  psychology  the  genetic  method  of  study 
is  ]Hirsued  lo  a  large  extent  in  the  works  of  Stanley 
I  lall,  (iroos  and  Baldwin,  ami  in  the  recent  volumes 
ot  Kirkpatrick  on  (ictutic  I'sycholoijy  aiul  of 
I'armelee  on  Ilmiiiiii  Bfhaiior.  Modern  "phi- 
losophy ot  education"  has  been  inlluenccil  in  no  small 
degree  by  studies  and  speculations  in  comparati\e 
psychology,  aiul  especially  in  this  country  by  those  of 
Stanley  1  lall  and  his  school.  Ihc  doctrine  of  re- 
capitulation figures  (]uite  largely  in  the  writings  of 
this  school,  and,  while  the  results  of  its  applica- 
tion ha\e  not  always  been  happy,  the  general  influ- 
ence of  1  lall  and  his  followers  has  given  a  strong 
stimulus  to  genetic  psychology  arui  the  scientific  stuily 
of  problems  of  education. 

Much  attention  has  been  de\oteil  to  the  experi- 
mental analysis  of  instinct.  The  complex  instincts 
ol  crustaceans  and  insects  have  been  shown  liy  means 
of  operative  experiments  on  the  nervous  system  to 
be,  to  a  large  extent  at  least,  capable  of  analysis 
into  reflex  actixities  of  the  \arious  segments.  |>A 
rainless  crayfish  will  walk,  eat  food,  reject  innu- 
tritious  substances,  defend  itself  when  seized,  antl 
perform  various  other  complex  acti\  ities.  I  When 
any  of  the  segmental  ganglia  of  the  nervous  cord 
are  cut  oft  from  communication  with  the  others  by 
severing  the  connecti\es,  the  appendages  of  the  cor- 


« 


■'""""'  I'^^y^l'ol'xjy,   tin-   Old  and  the  Nc,,       ^r 

■■-l-n^iin^^  scffrncnt  uill  rcsp.Hul  .-uiaptivclv  to  ,„anv 
^'-"■^''^'t  arc  applied  to  then.     M:.„v  „Mh.  ,„  " 

y-.plcx  acmmcs.f  the  animal   ,nav  he. .p,,,,:^ 

"\^-    the.    pcrtormancc   of    other    acts.      The    be 

;'-'-.Mheuhole:.nimaImI«ht!.e,-e,ardeclasthc 
;-'.'.;'   a  so,-t  of  social  cooperation  of  the  activi- 
-"'  't^  various  quasi-independent  nervo.s  gan.Iia 
^'  -nnot  say  that  the  seat  oMnstinct  in  tuch  an 
'-'•;-n  the, rain  or  any  other  part  of  the  nen- 
^vsten,        I  he    instnu,.    ..(    the    anin.al    are    the 
'"■•r   "'    ';s  K^eneral   organisation;  they   are   the 
--'n  oi   the  uorkin^s  of  the  or^ani     mechan- 


Nn 

:inil 

"11^    system. 

I'litconi 

i\pi 

ism.     J 


'l'l''"-'s   to   tht 


puments  mchcate  that  the  same  conclusion 
^'^    ^''^-    'nstmetn  e    behavior   of   y  ertebrates 

'"'"■"'•;'"^   ^^^'    -^^•■-1   instinct   uith    Herbert 
^I-ncer    as   "cunpound   reHex  action,"   .ve  nn     be 

'-■'-'- concluding  that  it  is  evervu  here  a    mti!^ 
•'  "fnjani/ation.  •i."cnon 


^^  Til  the  same  aim  at  analysis  a  la 

'M'k 


I'ffc  amount  of 


i  n 
i'l-o 

i.iin 
!'i  a 
I  '"■'•'lice  in  the  tievel 


'Pmcnt  of  :,„i,„al  psycholojrj. 


32 


SiiuIk^   ill   Jnniiiil   lithtiiinr 


may  [icrha[)s  suffice. 

Irom  the  standfioint  of  ;uKil\>.is  as  well  as  tfiat 
of  c\i>luti(m,  a  consitlcral'Ic  iiircrcst  attacliis  to  the 
IH-Iiavior  1)1  the  simpK-st  tonus  ot  lite.  I  lere,  il 
anywhere,  one  iniffht  e\|'eet  l)eha\ior  to  be  capable 
of  analysis  into  physical  and  clieniical  processes. 
The  l)eha\ior  ot'  the  l'iiit.)/o;i  for  this  reason 
has  attracteil  a  nunilier  ot  caret  ill  workers  who 
ha\e  ciuleavored  to  test  how  tar  such  behavior 
can  be  explaineil  in  terms  ot  siin[)ler  factors.  Jen- 
nings in  particular  has  done  a  larji;e  amount  ot 
careful  observational  work  in  this  field;  he  has 
shown  in  the  case  of  Amalia,  which  is  often  re- 
ferred to  as  an  almost  structureless  mass  of  jelly, 
that  the  behavior  is  surprisinj^ly  complex,  and  at 
present  incapable  of  beinjr  esplained  in  terms  of 
physical  and  chemical  laws.  This  does  not  imply 
that  the  behavior  of  .\n\(rba  is,  in  the  last  anahsis, 
incapable  of  such  explanatioti ;  it  simply  means  that 
t)ur  present  knovvled;^e  is  inadeiiuate  for  this  task. 
I'.ven  the  simplest  organism  is  a  very  complex  struc- 
ture from  the  standpoint  of  the  chemist.  And  it  is 
not  to  be  wondered  at  that  the  simplest  creatures 
often  act  in  ways  wliicli  we  can  neither  predict  nor 
explain.  Minute  stuily  of  the  behavior  of  the  low- 
est organisms,  however,  h.is  revealeii  a  remarkable 
amount  of  uniformity.  1  he  activ  ities  ot  these  tonus 
are  stereotyped,  yet  plast'c,  and  while  no  intelligence 
has  been  proven  to  c)ccur  m  any  ot  them,  their  be- 
havior is  often  capable  ot   modifications  in  various 


u.is>>  in  .ui.iptatioii  t(.  chaii^rcJ  cnJitlons  <,f  life' 

I  he-  hchav  i.,r  not  ..nly  of  tlu-  l'n.r<,/„a  Init  <.f  all 
limlicT   .lass.s   nf   anin.als   has   lu'cn    stu.iid    in    the 
l:>^r    leu    years    with    a    ^ix-.n    increase   ..f    /eal    anj 
tli'.rnuKhness.     The  activities  n(  hvJroi.is,  jelly-fish 
^••nns,  inoihisks,  ..chinodcrms,  crustaceans,  as  well 
:is  insects,  an.!  n  ertehratcs.  haxe  en^ra^rej  the  atten- 
f'""    ;.t    a    s.nall    anny    „f    investigators    who    arc 
'■apiaiy  amassinjr  a  vast  store  of  detailed  knowledjre. 
\   UTv  few  years  a^n*  there  was  established  a  spc- 
^'■'I  periodical.    Thr    Innnial  of  .huntal  Behavior 
devoted  cNclusnely  to  papers  on  animal  psvcholojry' 
while  an  increasing  amount  of  literature  on  the  suh- 
J^et  IS  ^oin^r  into  ,.ther  channels. 

liie  d=»ys  of  anecd..tal   psycholojry,   when  it  was 
ti.e  fashion  to  bring  together  stories  from  various 
-urces  illustrative  of  animal  sagacity,  are  passing. 
I  lie  psychological  interpretation  of  animal  behavior 
's   a   subject  that   abounds   in    pitfalls   for   the   un- 
^^ •"■>••      !<•   find   out  what  probably  goes  on   in   an 
"'■|"'>Is  mind  re.juires  close  and  continuous  obser- 
^'itmn    and  usually  experiments  under  carefully  cun- 
tn.l  ed  conditions.      Fhe  careful  experimental'work 
■"    llu.rndike.  Cole,  Yerkes,  Ilobhouse,  Small  and 
"u-  other  investigators,  has  gis  en  us   a  more  ev- 
■ut  knowledge  of  the   mental   activities   of  the  ani- 
HKds  studied  than  would  have  been  possible  through 
';!c  collection  ot  any  quantity  of  scattered  observa- 
--"-       ri.e   results   have   sometimes   proven   disap- 
i"""r.ng  to   zealous  champions   of  the  high   mental 


( > 
III 


34 


Siud'u'^   ill  .hiiiiiiil  RiJiiivi'if 


iK\  cliipnuiit  (il   tluii'  .niim.il   irutul'.. 

I  Tlu  Tc  is  littK-  lir'Hirul  tOr  lulicx  iri;^  ili;it  ;mimals 
h;u  c  ;ihstr;ut  or  yciKTal  idcis,  nr  tlu'  I'duii-  (it  dc- 
lilur.'Ji'  rriisoniti;^,  but  tluri'  is  iniisuliTalilr  ixpcri- 
iiK'ntal  c\iikTicc  that  flu  y  liavi  iiKas  of  a  simple 
sort  ami  a  icrtain  poui-r  ol  iiilcri.iKi.1  Carrtul  iii- 
\  I'sti^liators  at  pri-scnt  show  a  u  Iiolcsoriic  lautmn 
about  astrihiii^  to  the  iiiiiul  ol  the  animal  ?norc 
than  the  faets  reali\-  lustily.  I.Ioyil  Morgan  has 
laiil  down  the  principle,  since  known  as  the  jirinciple 
of  Morgan,  that  no  act  should  he  ascribed  to  a 
higher  mental   faculty  if  it  can  he  satisfact<irily  ac- 


coun 


ted  f 


or  m  terms  ni   a  low  cr  oiu 


The  burden 


ot  proot  is  thus  placed  upon  those  who  cotitend  lor 
the  superior  endowments  ol  the  animal  mind.  What 
we  watit  are  not  stories  ot  pertormances  which 
i\e  in\  t)l\ed  unusual  intellijrence,  hut  records 


mi 


jrht  h 


«>t  aciiie\ements  wliicli  cannot  be  accomplishcil  ex- 
cept by  means  ot  unusual  intellif^cnce.  In  the  latter 
case  onlv  are  we  iusritieil  in  ascrihiiiL;  to  tlie  animal 
the  mental  attribute  in  i|uest:on.  In  loMo\\In|r  the 
principle  ot  Morgan  we  may  otten  tail  to  )^i\e  to 
the  animal  full  credit  for  the  faculties  it  may  really 


possess, 


but 


owj-  conclusions  will  be  souiitl  so  tar  as 


th 


cy  go. 


11 


I  "I      I  \Ol  I    ll,,\    ,,|      I'AKI  \r.M.    CAKi. 

I  \M  INC  JS    tor   ihc    caro    <.f   ynunir   ,vtnul    far 
''"^^"    "^    tl'^-    animal    kln^rjon,    ;nul    their    nriL,rin 

""•'vl-r.  Jat.s  l.uk  n,  an  c;.rlv  pcri.nl  inth,  history 
'    "HYarth.       Ih,   important   role   uliich    these   in- 
""^tshaveplave.i  in  the  ev  ..Jution  of  anin.aliife — 
■•  '"I^  uiueh  has  inerease.j  in  irnportanee  as  aninuls 
I'ave  l^ec.Hne  more  hi<rh|y  e volvecl,--ren.iers  the  suh- 
l^Ht  ot    then-  ori^r,,,  anJ  course  of  e\oluti..n  one  <.f 
-IHu.'l    interest    to    the    con,parative    psycholo^nst. 
\^"lia  tnllrca,.     'tion  of  the  fact  that  phvloj^cny  is 
•;'■;■';'—  fuKI    I    have  nevertheless  venture.l   in 
"';;    "II.'wmK  account  to  outline  the  pn.hahle  way  in 

;'"^'-  ••n-nals  can.c  to  care  for  their  offspring,  anJ 
"•  P'""t  out  hnelly  ho,,-  parental  care  has  heen  in- 
^''"'"-'f'N  "'  shapi,,;,  the  ,n.re  advaueed  stages  of 
'ii'-  <\nlutioiiary  process. 

'"   s^'w^i-al  respects,   no.aMv  i„    ,,I,ti„„   ,„  ^„^._,, 

•"•1  ^thicaleyolut.on.  the  institution  of  parental  care 
''-'"'•■ncithe  loundation  »'m-  hij^her  stages  of  de- 

;;^"l--y  >'-^-i/ed  societies  in  animals  generally 
'•'^^  then-  bc-mnuijr  ,„  the  expansion  of  the  family 
'n  M.n,e  msects,  for  mstance,  such  as  the  ants,  bees,' 
-Hial  vyasps.  various  i.ra<h;rions  may  be  traced 


.m 


OD 


.K^ 


.S'///(//(>    ill   .liiiiiiiil    Brlidi'iof 


between  the  ^iiniilc  f;iinily  aiul  the  h\^h\\  or^aiii/eil 
social  state.  Maii\  insect  coniinunities  c()nsi^t  merely 
of  an  enormous  family  resulting  from  a  sinij;le  fe- 
male |)arent;  ami  when  the  community  includes  more 
than  this  the  conilition  is  t:jenerall\  a  secondary  out- 
}jro\vth  of  the  domestic  ji^roui''. 

In  the  care  of  parents  for  their  yoiuifj;  wc  proh- 
ably  lind  also  the  lii'st  traces  of  altruistic  instinct. 
I'amily  life  is  impossible  on  the  basis  of  purely  eirois- 
tic  behavior.  Some  altruism.  ho\\e\ei'  weak  and 
limiteil  in  its  scope,  is  the  essential  condition  ol  the 
family  ^roup.  In  low  lorms  it  is  limited  to  the  care 
for  oftspi-in^;  later  it  may  include  other  members  ol 
the  species  beyond  the  limits  of  the  family;  hut  it 
is  a  lon<i  time  before  it  extends  its  blessin<j;s  at  all 
wideU.  Most  creatures  care  not  a  liu;  lor  the  wel- 
fare of  any  but  ttieir  own  imniediate  kin;  and  where 
we  iind  any  consiileratioii  bestowed  u[ion  alien  lorms. 
as  in  the  fostering  of  :i})hids  by  ants,  it  is  lIouc  f(U- 
the  sake  of  soiiiethinu;  to  be  tfained  in  return.  .\ni- 
mals  in  general  li\e  under  conditions  in  which  they 
cannot  afford  disinterested  benevolence.  While  tlie 
long  hard  struggle  for  existence  rnay  ha\e  bred 
tender  feelings  and  unselfish  impulses  it  has  pro- 
duced them  for  the  same  ultimate  purpose  that  is 
subsei-\ed  by  sharp  claws  and  good  teeth, — the  sur- 
vival and  perpetuation  of  the  species.  Parental  care 
is  one  of  Nature's  devices  for  race  survival.  i5ut 
very  few  of  the  devices  which  Nature  has  hit  upon 
have  influenced  so  profoundly  the  course  of   evolu- 


Th,    F.vi^hillcni   of   Pairutiil  Care 


37 


!i"n  in  the  liiM;licr  animals. 

Wc  cannot  nf  co-irsc  follow  step  I,v  strp  all  the 
M,i-cs  in  the  e\..lution  of  the  parental  instincts  and 
Kehn.trs.  but  hy  a  comparative  siir\  ev  of  the  .'nimal 
iMM-doni  it  is  possible  to  construct,  with  some  d-^y,-c 

'»  l"-"'^''I'>litv.  the  main  outlines  of  this  development 
\inon-  the  lower  invertebrates  the  .)Hsprinjr  have  to 


■'lilt    lor   themselves   at   the 


II-   \ery   lirst  a[)pearance 


•i'-n  tl'c  sta.^e  of  ]\\,.     There  are  sometimes  devices 
MKh  as  brood  pouches  for  the  protecti.ui  of  tlie  e^rjrs 
■;'•  \"unir.   but   an>    active   solicitude   of   parents   for 
'•'"n-  ..Hsprni.ir  does   n..t  appear  until   we   repch  the 
h.U'her  invertebrate  animals.     This  lack  of  parental 
'it^ivst  ,s  well  dlustrated  bv  the  behavior  of  an  am- 
'H';^l    crustacean.    Amphithoe,    which    the    writer 
^■udiedms.mie  detail  a  few  years  a^o.     In  this  form 
;iu'  eu^rs,   and  ako  the  youn^  for  a    few  davs  after 
^in.i:  hatched,  are  carried  in  a  brood  pouch  on  the 
'■"der  side  <.(   the  hodv.     When  sufHcientlv  a^rjle  the 
-"_m-  make  their  way  out  of  the  brood  pouch  and 
-^'",  awav.  the  mother  payin^r  „„  niore  attention  to 
'''^",  than  to  anv  <.ther  animate  obiect.     Indeed  the 
-"•"'^"■•'.us  habits  of  this  species  make  it  more  or 
;>  danjrerous   for  the  younjr  to  tarrv  lonjr  j,,  the 
'  'Huty  of  their  parent.     .Several  times  I  have  cau-dit 
"•^'  .^'"i.ii^r  ,,,  a  line  pair  of  forceps  and  otiered  them 
"  '"^'  mother,  who  ate  them  without  the  least  cnm- 
'^r'T-      !'    ''    ""''    "'    '    ^'-"^^'v    material    senie. 

'iHTefore.  that  Amphithoe  can  be  said  to  be  f<,nd  of 
iis  uftspring. 


38 


SniJ!(\< 


nt 


hiliitiil   Ri'litizior 


So  lar  as  tiic  writer  i*;  aware  the  satin,  utter  lack 
ol  maternal  sentiment  enaraeteri/es  all  the  criista- 
eeans  as  well  as  the  numerous  varieties  of  worms  and 
mollusks.  Amon^  the  arachnitis  la  ire  has  clescrihed 
how  the  temale  scorpion  assists  her  vountj^  to  hatch 
by  caretully  tearini^  awav  the  e<^u;  memhi'anes  with 
her  jaws.  \\  hen  the  tin\  scorpions  are  liherated 
they  have  the  cuiaous  habit  ot  mountin!:;  upon  the 
back  ot  the  mother,  who  tor  a  perioti  ot  several 
('ays  remains  closely  continctl  to  her  nest.  In  the 
.jiiders,  although  as  a  rule  only  an  attituile  ot  hos- 
tility is  manitested  toward  other  members  of  their 
own  kind,  the  runninu;  spider  Lycosa  carries  her  co- 
coon about  with  her  and  when  the  youni:;  spiderlinujs 
are  hatchjd  they  elinu;  in  a  sijuirmin^  mass  to  her 
body.  1  he  mother  ilocs  not  teed  or  acti\elv  care 
for  her  younj^  in  any  way,  and  it  is  doubtt'ul  it  ma- 
ternal care  goes  further  than  a  sort  of  gouil-natured 
tolerance  of  her  lixinL";    uinlen. 

There  is  much  e  ience  for  the  su[iposition  that 
the  first  step  in  the  e\(dution  of  parental  care  was 
taken  in  the  formation  ot  instincts  to  secure  the 
proper  einironment  tor  the  de\  elopment  of  the 
eggs.  Instincts  for  depositing  eggs  in  places  which 
afford  foo(.l  for  the  young,  instincts  for  making  co- 
coons or  other  receptacles  for  the  eggs,  antl  instincts 
for  concealing  the  eggs  from  the  attacks  of  other 
animals  are  common  in  animals  which  are  too  primi- 
ti\e  to  exhibit  any  care  for,  or  even  recognition  of 
their  own  offspring.      Many  mollusks  plaster  their 


/ //('   Eiolulion   of   Parrnliil   ('.,n, 


.^9 


1 

-■i. 

J 
■5? 


i<4tJ:^  oil  stones  or  ;i(]uatic  plants  m-  Iniry  tlKiii  in 
:(cIar!iious  lasses  in  the  sanJ.  hut  tliey  certainly 
Im\^'  not  th     least  jrliniiner  oT  an  iilca  coiuerninfr  the 

nsr.      fhe    cahha^e   hiitterHy   instincti\  elv   deposits 

.is  L.urnrs  ,,,1  cali|)a^res  or  otlier  cruciferous  phmts,  the 

!><it  ilv  oviposits  upon  the  hairs  of  horses  and  cattle, 

:'iJ  ihc  Alay  fly  drops  its  ei:ifs  into  a  pund  or  stream, 

r  It  is  utterly  out  of  the  (juestion  to  suppose  that 

;\    "I    these  creatures   has  the    remotest  notion   of 

"■    l.ir\a-   tfiat   wili    isMie    from   its  e^t^rs,   much    less 

I    tile   relation  of  tlie  environment  i4   the  cfrgs  to 

'ill'  needs  of  larval  life. 

\   lurther  step  in  the  direction  of  parental   care 
is  taken  Iiy  the  solitarv   wasps.     In  manv  species  the 
t;  male  ch<rs  a  hole  and  then  goes  in  search  of  a  par- 
rieular  kind  of  Insect  or  spi.ier  to  serv  e  as  food  for 
her  young  gruh.     Tlie  victim  is  stung  in  such  a  way 
i!i:'t  it  is  paraly/ed  hut  not  killed,  so  that  the  young 
•in  luc  upon  food  that  is  not  decayed.     Then  the 
Pi-cv  is  stored  in  the  hole,  an  egg  la'id  upon  it,  and 
the  h.ile  Idled  up  with  dirt  and  left,  the  mother  nev  er 
o.mmg  hack  to  see  how  things  fare  with  her  voung, 
nnr    concernmg    herself    further    with    Its    welfare. 
1"   tact,   most  of  these   wasps  never  see  their  own 
j'l-ngenv,  and  show  no  signs  of  recognition  when  the 
l-u-viL'   are   shown    to   them.      All   the   wonderful    in- 
■^tinctiv  e  acts  hy  which  the  solitary  wasps  pro\  ide  so 
■>ul!    tor  the  needs  of  their  larva-  are  hlindly  per- 
''•nned,  and  give  no  indication  of  any  feeling  of  pa- 


40 


Si,(,l 


/(■»   / 


//   .liiinid!   Biliiii 


Kir 


••cntal  altcctinn,  c\cn  of  the  most  ru(.linicnt:M-v  sort. 


A    more   luKaiuetl    stairc   in   the   evohiti 
rental   eare  eon:es   with  the   a[ipearaiue  o 


ni- 


.  list  I  nets 


f 


or  more  or  less  continuous  care  ot    the  e^^s  after 


thcv  are  laid.    If  the  coeooii  of  the  run 


nnu 


IS 


takt 


spiiier 


en  away  trom  her,  which  is  lione  only  atter 
a  certain  resistance,  she  will  ea;^erly  sel/e  it  a^ain  if 
she  ha[i[Hns  to  encoLinter  Ir.  I  he  e<i^  mass  is  treateil 
as  an  ohject  of  interest,  althoiii^h  the  youn;^  which 
issue  from  ir  arc  rej^anled  with  Muhtterence.  in- 
stincts for  remainins^  with  tlie  eyj^s  lor  a  lor.ircr  or 


shorter  tune  after  tliev  ai' 


1.    tleposl 


ai-c  not  mrre 


(juiiit  amonff  lishcs,  and  especiallv  amonLi;  tliose  spc- 
cies  which  expend  some  labor  In  the  construction  of 
a  nest.  ( lenerally  this  task,  is  performed  In  the  male, 
as  in  the  sticklebacks  antl  the  con 
fish  of  our  ponds  anii  streams. 


unon  .\mia  or  dog- 


Ih 


e  males  o 


f  tl 


use 


ishes  remaui  in  or  near  tlie  nest  alter  the  et^r^s  are 


laid. 


and 


tl 


ie\   keep  on  the  alert  to  lirne  away  any 


intrutier  that  \entures  too  near. 


)  are  remar 


kal 


ile 


f. 


I  he  Amphibia,  which  as  a  ;.!;rou] 
r  (|ueer  breedinir  habits,  show  in  many  cases  primi- 
tive instincts  for  jruartiing  or  at  least  remaininjr  close 
by  the  ejTffs  during  the  early  stages  of  their  deyelop- 
ment,  although  most  s[iecies,  as  in  our  ordinary  frogs 
and  toads,  simply  abandon  their  eggs  as  soon  as  they 
are  deposited.  The  newt  Dcsmognathus  lays  its 
eggs  in  a  small  hollow  ami  remains  near  them  for 
some  time.  I'he  snake-like  ca'cilians  coil  about  their 
egg  masses,  and  (.crtaia  species  uf  frogs  carry  eggs 


7//<-   Einlitl'mn   of  Pantual  Can  41 

,11  pouclirs  on  tl:.'  hack  or  in  sacs  connecteci  wifh  the 
throat.  One  of  the  most  peculiar  cases  is  affonied 
bv  the  ohstetrical  toad  of  luirope  in  which  the  male 
^.irrics  the  string  of  e^vs  coiled  ahout  his  hind  legs 
until  the  young  are  ready  i  ^  hatch. 

\\  hdc  the  Amphihia  in  some  cases  exhihit  a  cer- 
tain care  for  their  eggs,  they  all  appear  to  be  utterly 
iiullHerent  to  their  young.  One  reason  for  this  is 
the  fact  that  the  young  usually  live  in  the  water 
■Ahile  the  parents  are  often  terrestrial,  hut  another 
reason  is  doubtless  to  be  found  in  the  low  psychic 
.le\  elopmcnt  of  these  animals. 

Kcptilcs  as  a  class  concern  themselves  very  little 
ah'Hit  their  progeny.  The  latter  arc  (juite  well  able 
t|'  take  care  of  themselves  upon  their  first  introduc- 
-"11  into  the  world.  Alligators  are  said  to  watch 
"\er  the  places  where  their  eggs  are  buried  in  the 
saiul.  and  pythons  coil  around  their  eggs  and  help  to 
inuihate  them  by  the  warmth  afforded  by  their  bodies. 
Sohcitude  for  their  eggs  is,  however,  very  rare 
I'tiong  the  reptiles,  and  active  care  for  their' young 
is  practically  absent. 

W  iih  the  birds,  which  as  a  group  are  remarkable 
I'"-  their  parental  and  fostering  instincts,  care  for 
tiic  eggs  appears  to  be  universal,  and  with  rare  e\- 
ainions  the  birds  sit  upon  the  eggs  until  they  are 
'iitched.  There  has  been  much  speculation  concern- 
ing the  origin  of  this  curious  instinct  of  incubation. 
\s  Whitman  has  remarked,  "the  incubation  instinct 
^vas  supposed  to  haxe  arisen  after  the  birds  had  ar- 


42 


St„J 


/(■>  III 


.} 


II  I  III  (I 


I  lUl 


idliar 


ri\  ctl  aiiii  la'ul  their  c^ifs,  uiiicli  woiiKl  lia\  c  been  Icit 
to  rot  li:ui  not  some  birds  just  blundered  into  cud- 


dim^  oxer 


rl 


lem    am 


resciieei 


the 


i; 


ne    I  rom   extuu- 


tion. 


A  litt' 


e  re 


lection  nia 


ker,  it  e\  ident  that  such 


an  orij^in  is  clearly  inipossipie. 


and 


that 


\vc  must  }^() 


back  probably  to  the  cold-lilooded  rejitilian  ances- 
tors of  the  birds  lor  the  beji  nnin^s  ot  the  instinct.  A 
comparatixe  sur\e\  of  the  beha\ior  ot  the  more 
primiti\e  animals  toward  their  et^L^  makes  it  prob- 
able that  the  instinct  ot  incubation  ^rew  out  ot  the 
instinct  to  r';main  m  uv  near  the  place  where  the 
cirtrs 


the 


the 


a  re 


deposited    tor    the    pur[iose    of   proteciitiL; 

em.      l.\inL!;  near  or  broodintr  over  the  e;j;^s  may 

iHcnuleii,  even  in  the  cold-blooiied  amestors  of 

e  tMrils,  sutHcient  heat  to  make  the  eii;^s  dexelop 

ie  aihaiuaLie  tlius  accru- 


with  increased  rapiility. 


n 


mu;  to  the  species  may  liave  caused  the  protectniLi; 
instinct  to  liexelop  iurther  into  a  true  instinct  tor 
incubation.  With  the  de\  elopment  oi  warm  bU)0(.l- 
I'dness  which  went  on  tluriiiLj  the  cxolution  ot  the 
liirds  from  tlie  reptiles  the  supplyiiiL^  of  artificial 
heat,  at  tirst  only  a  means  ot  hastenin<r  i.ie\  elopment, 
became  an  itulispensable  condition  of  iie\  elopment. 
Dependence  upon  artificial  heat  must  have  been 
e\ol\ed  /•</;■/  /'J -mi  with  the  de\  elopment  ol  the  in- 
stinct t<w  inculcation.  C  ertainly  the  latter  never 
could  have  been  developed  after  tlie  former  had 
been    established. 

There    is    much    evidence    to    show    that   the    next 
step   toward   the  ilev  elopment  ot    parental   affection 


i 


rill'    Eioliitidu    of    Par,  ntiil   Car,- 


43 


V.  >s  I>i-oii-|,t  :,I„.ur  hv  the  cxtcnsi..,,  -t  circ  f..|-  rjr^r, 
-  uhar  cunics  ,nit  ..f  rlir  cu-s.      little  m,.,v  than'a 
I'-hMc  lv,^r,n„i„^r  ,,(■  sucl.  ;. ,1  cxtCMsion  naurs  amon^r 
-ini'  ..(  the  arachnids  t,.  which  wc  have  already  al- 
'     !>■''•      'n  most  insects,  althoii^ri,   p,-<.\  isi.,n    (..r  the 
■.-  >s  cnniMH.n.  the  parents,   with    rare  exceptions, 
'    iilterly   nuhtferent  to  their  younjr.      Amon^'  the 
-m:iI  insects,  :,o\ve\  er,  such  as  the  ants  and  bees,  the 
^"im-  ^rruhs   are   tended    with   scrupulous   care.      In 
the  solitary  bees  anil  in  many  of  the  more  primitive 
-Hial   species  the  ej^rtrs   are   laid  with   sufficient  pro- 
-I'.ns  for  the  entire  life  of  the  larva-  and  then  left 
^•'tlK'ut  further  attention.     "Idle  transition  from  this 
•i'it""i  to  one  in  wliich  food  is  brought  to  the  cells 
■""    t!ic  larNa-  are  hatched  Is  an   easv  and   natural 
■"-["Pnient.      And  as  we  pass  to  the  more  hijrhlv 
I  ^  Hoped   social   jrn.ups   such   as  the   hive   bees   the 
•i^ti.uts    tor  taking  care  of  the  larva'   become  more 
\;'eciall/ed  and  more  complex. 

Anir.n.;-  the  xarlous  species  of  lishes  that  bestow 
-""^'  'are  upon  their  cv^^,  there  are  some  forms  that 
P'v  lu.   particular  attention   t,,  their  newly  hatched 
•  -^n-  which  scatter  as  soon  as  thev  emerfre  from  the 
^^  n-m.trs  of  the  ejrjrs.   In  other  cases  such  as  the  do^r. 
'-1  Amia  the  protecting  instinct  is  c-..end.'d  to  the 
^''un«  brood.     '1-hc  male  parent  swims  about  with  his 
Hhno    of  small    fry  and  keeps  many   enemies  at   a 
-ilc  distance,  for  he  is  an  alert  and  valiant  defender 
"'  'Hs  own.     In  the  course  of  a  (csv  weeks,  however 
tfic  lamily  ties  are  broken,   the  little  iishes  become' 


44 


Sliit!if<   ill   .tiiiiiuil    firlidvi'if 


dis|Mrscil  far  ami  wide,  and  parental  M.ruitiuk',  lia\- 
in^  suhsi-rvcd  its  purpose  of  aftordinji  protection 
when  ir  was  most  needeil,  is  tnanifesteil  no  more. 

When  care  becomes  extended  from  the  e^rgs  to  the 
youn^  a  course  of  development  is  hetrun  in  which 
relatively  more  and  more  care  is  hestowed  upon  the 
oHspring  as  we  pass  to  hi^dier  forms.  Instead  of  a 
large  number  of  pro.i,any  left  to  shift  for  themselves 
with  a  consequent  great  loss  of  life,  we  Imd  in  the 
higher  animals  a  decrease  in  the  number  of  offspring 
combined  with  an  increase  in  the  care  and  attention 
devoted  to  each.  The  young  become  at  the  same 
time  less  able  to  take  care  of  themselves  and  are  de- 
pendent lipon  their  parents  for  longer  periods.  And 
along  with  these  changes  there  is  an  increase  of  sym- 
pn  hy,  affection  and  the  various  emotions  that  come 
into  play  in  the  family  relation. 

This  is  well  shown  among  the  birds,  'f'he  lower 
birds  la\'  manv  eggs  either  in  crude  nests  or  none. 
The  young  birds  which  are  (juite  acti\  e  when  hatched 
do  not  remain  long  untler  their  parents'  care,  and 
many  are  lost.  The  higher  song  birds,  on  the  other 
hancl,  lay  few  eggs  in  a  well-prepared  nest,  and  the 
young  which  remain  in  a  weak  and  helpless  state  for 
a  considerable  time  after  hatching  are  fed  by  their 
parents,  kept  clean,  and  protected  fron)  \  arious  ene- 
mies. There  are  few  more  fascinating  pictures  of 
domestic  life  than  those  afforded  by  the  little  family 
group  in  many  of  the  higher  birds. 

Among  the  mammals  we  may  trace  a  simila-  line 


Tlic   Fid/niioii   of  Pari'tilal  Can 


111  cMilution.  I  he  suckling  of  younf^  presupposes  a 
i^rtaiii  tdlcraiice,  it  not  re^rarJ,  on  the  part  of  the 
iii.tlier  for  her  oHsprin^r.  I  I;ul  there  not  been  among 
t!k  ancestors  of  the  mainiiials  a  fairly  elosc  associa- 
tiiiii  between  the  parents  and  their  offspring  during 
the  infancy  of  the  latter  there  obviously  could  not 
lia\e  been  cNohed  the  niainmary  glands  and  other 
tJaj)tarions  for  suekling  the  young  which  are  among 
tiic  most  fundamental  and  distinctive  features  of 
mammalian  structure.  Instinct  and  organization  are 
e\crywhere  closely  correlated  and  act  and  react  upon 
niiL  another  during  the  course  of  evolution.  The 
mammals  afford  an  interesting  instance  of  the  way 
111  which  instincts  of  parental  care  have  been  instru- 
mental m  developing  certain  fundamental  peculiar- 
ities ot  bodily  organization. 

C  ertain  writers  of  the  associationist  school  of  psy- 
th.ili.iry  ha\e  endeavored  to  explain  why  animals 
i^uard  their  young  with  affection  on  the  basis  of  the 
rchet  the  mother  experiences  in  ha\ing  the  milk  re- 
moved from  her  mammary  glands.  Bain  would  have 
us  believe  that  maternal  love  was  compounded  out 
<'t  numerous  agreeable  sensations  of  touch  experi- 
eiued  In  hamlling  t'  soft  bodies  of  infants.  Why 
Mic  mothers  do  not  develop  an  equal  fondness  for 
\  J\et-co\ered  cushions  the  theory  does  not  make 
^lear.  Such  explanations  appear  eminently  absurd 
m  the  light  of  a  comparative  study  of  the  relations 
"I  [)arents  to  offspring  in  various  groups  of  animals. 
I 'a  rental   care   must   have    antedated   the   giving  of 


Si  11(1  i 


I'S    III 


I 


mm 


til   [{ilhiii'ir 


lilt 


Ik. 


;iili 


1  it  is  prohaMc  that  withmit  parLiit.i!  attct- 


tmil      tlKTC      \V(H1 


1.1  hj  little  iiKii-f  foiitact  lutui'di 
parent  ariil  ottspriiiLj,  than  there  is  anionic  lishes  ami 
aiiipliihiaiis.  I  I'mii  the  u;eiielie  standpoint  hotli  ex- 
planations jnit  the  cart  helore  the  horse. 


LinonLC    annuals    ij^cw 


erally    | 


arental    atteetion    is 


rather  strictK   limiteil  to  the  perioil  ol  mlanev,  alter 


whieh   ther 


e  IS  a  ili>ri.i:aru  or  ii 


lulitlereiiee  that  eoii- 


trasts    slranncK    uitl:    our    own    natural    sentiineiits. 


I 


le  atteitions   ot    animals, 


lik 


e  most   ol    then-  othir 


eharaeterisl  Its,   are  (luite  eloseK    suho 


,-  i; 


nati 


to  the 


iieeijs   o 


t    tlu 


species ; 


when   llie   \ouiiu:   are   alile   to 


make  their  \\a\  in  the  worKl  alone  the  tunetion  ol 
parental  lo\  e  is  past,  ;!iul  the  leelinu;  rapullv  heeomes 
extinct. 


is  u  e  approacli  m.in  we  liiu 


I  a  len}.;theniiiij;  ol  the 
perioii  ol  intancy  aiul  a  prolongation  ol  tiie  time  liur- 
liifT  which  tlie  parents  bestow  their  care  aiul  atiection 


th 


upon  ttieir  ottsprmj. 


As  I 


oim 


liske  has  shown,  ''n 


leni^theniiii^  ol  inlaney  attonls  opportunity  lor  the 
younj^  to  ac.juire  experience  aiul  perlect  theiiisches 
the  \aricil  acti\ities  which  are  ilemamieil  in  the 


in 


lile    of 


i^lily 


c\(j|\  eU 


animal 


W 


I  ere, 


in 


hijrher  torms,  success  in  lile  depends  relati\ely  more 
on  intellijj;ence  than  blintl  instinct  it  is  important  that 
there  shoukl  he  a  period  ol  etlucation  in  which  the 
younjr  animal  is  nioro  or  less  shielded  from  the  hard- 


ith 


snips  and  tianjjjcrs  with  wlucli  it  will  luuc  to  cope  in 


11  h: 


nan    cousins    remain    wi 


th    tl 


leir 


later   life.      ()ur   sin 

youn^  lor   a   h'liir  perioil,   ai.d   exhibit   a   ilej^ree  of 


/ 


tcTuliTMcss  I'or  than  that  Is  h'ttic  s! 


;.    i   "I    c.r,a,n   k,„.|,  kept   un.kr  u,nl„K,,u„,  I, 
liulm,  ,,,  N„r,h  Alran.     <  .rphan  monkc,,  „,  ,v 

'^<-\s,  hoth  male  ami  tcrnalc." 


Jt  is  a  far  cry  from  the  cLnr-i) 


KKi""i'ti--Ltin^r  iiistificts 


ifs  own  maintenance 
The 


Paratory  sta;re  of  development  may  be  re.r.r  I    I 
;;;  <'ut,ro.th  of  the  prc^ess  of  X:^^'"'-^: 

-nple  acts  of  e,,  laying  there  June  to  h'uKI 
••^'-'-    actumes    uhich    n>ake    for    the    uelfare 


48 


Stn{lii'<i  in  .hiimol  lirlnivinr 


the  pr(»jj[i'ny,  Kaiiinj^  <iii  to  active  soliiitude  lOr  the 
youn^,  ami  thriue  to  social  instincts  which  liiially 
lilossoin  out  into  the  rich  etulowitient  ot  altruistic 
emotions  anil  sentiments  ot  highly  e\(>l\  cd  social  life. 
It  is  in  reproiluction,  which  is  essentially  an  altruistic 
acti\itv,  that  we  must  seek  for  the  roots  of  altruism. 


!■ 


th 


^oism  anil  altruism  in  their  primal  mam  testations 


ire  coeval  rather  triati  successive  phenomena. 


Thi 


primitive  organism  which  ^^rows  and  divides  by  fis- 
sion shows  us  the  )^crm  ot  hoth  of  tliese  traits. 


KM  I  Ul  NCI'S 


Bain,  .\.  1  he  emotions  and  the  will.  4th  ed., 
1S99. 

D.NKWIN,  C.      Tile  descent  of  man.     \.  V.,  1S74. 

I'AHKl.,  J.  n.    Souvenirs  entomolo^i(]ucs,    i.  <>. 

I'lSKi,  [.       The  meaning  of  infancy.     N. '\'.,  \()o(). 

IIoi.Ml.s,  S.  J.  Observations  on  the  habits  and 
natural  history  of  .\mphithoe  longimana.  Biol. 
Bull.  2,  i6j;,  1900. 


Mntlll.I.l.,    v.    C.       The    childhood    of    a 


nimals. 


I.ond( 


•n,   1912. 


MoKcw,    C.    I 


mimal 


iK'nav  lor 


I.ond 


on, 


19 


00. 


Pi:c-Kii\M,  Ci.  W.  and  I!.  (;.  On  thi 
and  habits  of  the  solitary  wasps.  Bull.  \( 
CJeol.  Nat.  Hist.  Soc,  1S98. 


instincts 
2,  W 


IS. 


Pycraft,  W.   p.      Infancy  of  animals.     N.   Y 


1913- 


Kiftri'ihis 


4'* 


:^nun^uu  y      ,1k     „un,l  l,is,„rv  ..|   \„,i,,,K, 

^f;-— .  <..  ,1.  \nin,:,i  :,„.,i',;„;.,. '  ^.: ,,, 

..^:.M;::;;,r'Yl,„„;::-;r"""^'"" -^"■^ 

U.UIM.v.   CO,       .\„i„„||,,,|„,.„^       , 

'-■  .M-„u.  H,„l,   ..„„.     W Isllule,   ,«;8 


Ill 


I  III        I  UOI'ISMS     AM)      I  1(1  IK      KI.I. Alios       1( )     MORI. 
(OMl'I.I  .K  Moni.s  or   I'.lll  \\  lOK 


T 


III',  subject  of  animal  licha\l()r  has  been  of  in- 
terest to  hunian  beings  from  the  earliest  times, 
but  it  has  not  been  taken  \ery  seriously  until  a  com- 
paratively recent  date.  The  ways  of  animals  were 
considered  curious,  interestiiif.?  and  in  many  ways  use- 
ful things  to  know  about,  but  the  jrreat  theoretical 
import  of  anii7ial  psycholoiry  was  unsuspected  until 
it  came  to  be  recognized  that  our  own  minds  are 
tlic  outgrowth  of  the  animal  mind,  and  that  to  obtain 
a  truly  scientific  human  psychology  it  is  necessary  to 
have  a  clear  insight  into  the  psychology  of  the  lower 


animal 


rom   w 


hich 


wc  are  dcscen 


ded.     X 


ear 


th< 


mitltlle  of  the  nineteenth  century  Herbert  Spencer 
enunciatcii  the  principle  that,  "If  the  doctrine  of  evo- 
lution be  true  the  inevitable  implication  is  that  mind 
can  be  understood  only  by  observing  how  mind  is 
evolved,"  and  he  boldly  plunged  forward  upon  an 
undertaking  to  remodel  the  science  of  psychology 
from  the  genetic  standpoint.  The  result  was  the 
publication  in    1H55,   four  vears  before  the  appear- 


ance of  the  ()r/,jiii  of  Sprdi's,  of  the  Principles  of 


l's\cli()l(u/\',  a  work  which  for  sh 
'd 


eer  originality,  inde- 
[lendence  of  treatment  and  profouml  grasp  of  the 

50 


>-aWJ,i^-'.;i':.  ,■■> 


'-■"mem  of  ,hc  ,„.,ual  life  ,„;■„;''  ',    ""'"-"K 
al>Ie  am    ojlmnal  ,.|,,,„,,.,.  ■'"""»l*-     'lie  ailiiir,-. 

'"™tal  p„„,-,-s  of  „  ,„  a„J  ,1     ,  '""■'* ""■ 

/'■-.'-v- .u,,„,  a„:,  h'l  ton  n. /•":'' '"'''^; 

"■^-  c«o«  ei:n  :/  ,t:  r;'',:' "'  "'^"-"''-  '■'■ 

^>rt"  itie,  l,v  re.ol,  i      ..  mechanism  ot  animal 

""■re  and  more  to  I,e  en.olov,  ,       ,     ,   ''  ""  """'"S 

.;^'!''-'-oinve«i,.ei  '  \e;;::i;f"''y'^ 


52 


Sliidics   i.i  .iuimul   achaiior 


may  lock  forward  to  a  rapid  increase  in  our  knowl- 
edge and  insight. 

From  the  standpoint  of  analysis  the  subject  of 
tropisms  is  one  of  great  import.  Certain  stimuli 
exercise  a  directive  effect  upon  the  movements  of 
animals,  causing  them  to  go  toward  or  away  from 
the  source  of  stimulation.  The  moth  Hies  toward 
a  candle;  infusorians  gather  in  regions  of  dilute 
acids  and  avoid  regions  of  too  great  heat  or  cold; 
certain  caterpillars  tend  to  crawl  opposite  the  di- 
rection of  the  force  of  gravity.  These  directed 
movements  are  commonly  called  tropisms  but  there 
is  a  variety  of  opinions  regarding  the  kinds  of  be- 
havior to  which  the  term  tropism  may  be  applied 
and  usage  has  not  settled  authoritatively  upci  any 
rigid  definition  of  the  word.  We  shall  therefore 
use  the  word  in  a  somewhat  broad  and  indefinite 


sense. 


Tropisms  have  long  been  recognized  in  plants. 
The  familiar  phenomenon  of  the  turning  of  plants 

»  to  the  sun  was  termed  heliotropism  by  De  Can- 
dolle  in  1S35,  and  he,  in  common  with  several  other 
botanists  in  the  early  and  middle  parts  of  the  nine- 
teenth century,  regarded  this  turning  as  a  direct  and 
more  or  less  mechanical  effect  of  sunlight  upon 
the  tissues  of  the  plant.     Sachs  on  the  other  hand 

,  emphasized  the  aspect  or  irritability  in  tropisms, 
and  maintained  that  it  is  the  direction  in  which  the 
rays  of  light  penetrate  the  tissues  of  the  plant  and 
not  merely  the  different  degrees  of  illumination  on 


•'(»<-()  to  the  phenomena  of  trooismQ  in 
d  kctions  or  consc.ous  choice  of  animals  for  cerfaTn 

'■'"•   in   a    similnr  .         ^^  ^'  ''"*'-'  ''^^'^-""nted  ' 

,  '   ,  ^"'^«'""  •^«"'-J^''i  l>y  the  sunshi,,,.     A  some-  ' 
"''•"  more  anthrop.„„„rp|,ic  interpretation  „l  TZ 

l"----ug,e«cdb>H„n.ne.l,ir.4:,y 


54 


Stmrns  ill  .liiimal  Bchai'ior 


the  moth  llics  into  the  tlainc  of  a  camllc.  'i'hc  con- 
clusion arri\c(l  at  was  that  the  iiu-.th  was  drawn  to 
the  fatal  flame  out  of  curiosity,  or  the  desire  of  in- 

;\esti;;atiMfj;  what  manner  of  strange  object  a  candle 
llame  might  be. 

Ihe  theory  (.le\  eloped  in  Loeb"s  I  /  rliotrcpism 
stands  in  a  sharp  contrast  to  the  anthropomorphic 
views  of  ins  predecessors.     Orientation  of  animals 

,to  light  is  supposed  to  take  place  in  a  iTiore  or  less 
mechanical  fashion  like  the  orientation  of  plants. 
"These  tro[)isms,"  he  says,  "arc  identical  ff)r  ani- 
mals and  plants.  The  explanation  of  them  depends 
tirst  upon  the  specific  irritability  of  certain  elements 
of  tile  bodv  surface,  and  seconil,  upon  the  relations 
of  symmetry  of  the  boiiy.  Symmetrical  elements 
at  the  surface  of  the  boily  ha\e  the  same  irrita- 
bility; unsymmetrical  elements  have  a  difterent  ir- 
ritability, riiosc  nearer  the  oral  pole  possess  an 
irritability  greater  than  that  of  those  near  the  aboral 
pole.  J  hese  circumstances  force  an  animal  to  orient 
itself  toward  a  source  of  stimulation  in  such  a  way 
that  symmetrical  points  on  the  surface  of  the  body 
are  stimulated  equally.  In  this  way  the  animals 
are  led  without  will  of  their  own  cither  toward  the 
source  o5  the  stimulus  or  away  from  it."  The  moth 
flies  into  the  llame,  not  out  of  curiosity  or  any  other 
conscious  motive,  but  simply  because  it  cannot 
help  it. 

In  a  very  instructixe  scries  of  experiments  Loeb 
showed  that  heliotropism  in  animals  obeys  the  same 


Tropisms—Rclalnm  tn  MnJiS  of  Brluninr 


55 


laws  as  heliofrnpism  in  plants.     In  both  plants  and 
aniinais  it  is  the  direction  ,.f  the  rays  that  controls   ' 
the  direction  of  movement.     In  both  plants  and  ani- 
mals it  IS  the  rays  nearer  the  violet  spectrum  that 
are  the  more  potent  in  evoking  the  hcliotropic  re-  ' 
sponsc.      In  both  plants  and  animals  temperature 
piTMous  exposure  to  light  and  other  external  fac- 
tors influence  reactions  to  light  in  much  the  same 
^yay.     Back  of  all  the  differences  of  form  and  func- 
tion of  plants  and  animals,  and  notwithstanding  the 
I'lgher  organization  of  the  onimal  world  with   its 
specialized  sense  organs  and  complex  nervous  sys- 
tems the  living  substance  of  organisms  possesses  cer- , 
tain  fundamental  common  properties  of  irritability 
lipon  which  the  common  and  fundamental  features 
of  behavior  which  wc  call  tropisms  depend 

1  he  theory  of  Loeb  would  sweep  away  all  higher 
psychic  factors  in  the  realm  of  tropisms,   and   re- 
duce the  phenomena  to  comparatively  simple  mani- 
festations of  refie.x  irritability.      Further  he  would 
"plain  much  of  the  so-called   instincts  of  animals 
as  a  result  of  these  tropisms.     Since  the  prospect  of 
Ending  a  mechanical  or  causal  explanation  of  ai.y 
feature  of  behavior  is  always  an  alluring  one,  it  will 
he  of  interest  to  pass  in  review  some  of  these  cases 
of  tropisms  with  the  end  of  determining  how  far 
the  reflex  theory  will  carry  us.     And  then  we  shall 
consider  the  relation  of  these  tropisms  to  more  com- 
plex torms  of  behavior. 

An  excellent  illustration  of  a  tropism  is  afforded  by 


56 


Stndirs   in   .Inimtil   liduninr 


llic  li^,'ht  reactions  of  the  larva-  of  the  marine  worm 
.IrrnunUi.     These  larva'  are  ohlon^r  i„  shape,  with 
two  eye  spots  at  the  anterior  end.     Near  either  ex- 
tremity there  is  a  hand  of  cilia  hv  means  of  which 
the  larva>  swim  through  the  water.     'I'he  larvie  are 
P-sitive  in  their  reactions  to  li^rht.  and  will   follow 
a   liRht   around   in   various   directions.      Orientation 
to  h^^ht  is  hr.nijrht  ahout  hv  hendin^r  the  hody  to  the 
stmuilated  side.     If  the  larva  is  hetween  two  sources 
<^t  light  from  which  the  rays  intercept  one  another 
as  they  fall  on  the  ani/nal  at  an  angle  of  ninety  de- 
grees, the  lar\a  will  take  a  course  midway  hetween 


the  two  lights.     If  one  light 

hentls  immediately  to  the  other  one.     \\ 


is  turned  off  the  1 


arva 


a  mirror  so  as  to  throw  a  small 

ferent   parts   of   the   body,    Mast  has    sh 


y  arranging 
spot  of  light  on  dif- 


own   that: 
irown  into  one  eye  there  is  a  strong 


when  light  is  tl 

1  .  ,  -J~        '~        •-'       "        JLIUH 

licnj  ot  the  hody  toward  the  stimulated  side.     Th 


parts   hehinil   tl 


le    eye   spot   show   no    definite    reac- 


tion.    It  is  e\  ident  that  orientati 
due   to  ilitferent  intensities  of 
sides  of  the  hody.     So  f 


on  in  this  form 


IS 


liiumination   on   two 


ar  as  can  he  ascertained 


cntation  takes  place  directly  and  auto 


ori- 


out  any  conscious  decision  on  the  part  of  th 


matically,  with- 


Ih 


mo 


\ements    of    the    larxa 


\ oluntary  than  the  precise  m 


e  animal, 
appear   little   more 


to/.oa  or  th 
animal 


o\eme 


nts  of 


certain  Pro- 


e  swarm  s 


s  somewliat  hi 


■pores  of  algic.     Let  us  pass  to 
gher  in  the  scale  of  life. 


Some   years   ago   when   on   the   Atlantic 


Woods  Hole,  Mass.,  I  studied  the  beli 


coast   at 
avior  of  vari- 


Trnpisms—Relauon  in   Mndcs   of  nrliavinr 


-•>  / 


ous  a.nph.pod  Crustacea  „f  that  rc^non  and  particu- 
larly  the    reactions    „f   the    terrestrial    species    cu,n- 
>"»nly  called  sand  Heas.      It  is  a  son.euhat  curious 
circumstance  that  the  a.iuatic  an.phipods   are  ne«a- 
t'vc  to  hjrht  and  tend  to  keep  in  the  darkest  part  of 
their  enyironn.ent  while  the  terrestrial  ones  are  usu- 
^'lly  positive.     Positive  phototaxis  is  the  most  pro- 
nounced  in  the  most  terrestrial   of  the   species,   the 
lar^c    lalnrcluslia  Unujuurms,  uhich  lives   in   holes 
111  the  sand  hi^h  up  on  the  heach.     When  duj^  ot,t 
of  the  sand  these  crustaceans  usually  lie  curled  up 
'n  a  death  feint,  hut  when  they  become  active  they 
jnan.fest  a  very  stron^^  tendency  to  hop  toward  the 
ignt.      When  brought  into   a   room   they  may  keen 
Ijopping   toward    a    window   with    intervals    .'.f   rest 
during  the  entire  day.     If  they  are  placed  in  a  dish 
one-half  of  which   ,s  shaded   while   the   other  half 
's   exposed   to    the    direct    sunlight    they    will    keep 
hopp.ng  toward  the  light   until   they  are   overcome 
">  the  heat  of  the  sun's  rays. 

The  smaller  OrchcsUa  ayUh,  which  lives  nearer 
he  waters  edge  and   fre<,uently  manifests  a  nega- 
tive reaction  to  light,  shows  the  same  fatal  degree 
-'^  positive  phototaxis  when  exposed  for  some  time 
o  strong  sunhght.      Does  light  orient  these  forms 
automatica ly  and  involuntarily  as  is  apparently  the 
csewiththe    arv.of./.W..^     ''!--  --ev- 
ral  facts  which  favor  such  an  Interpretation.     The 
ersistent   and    apparently   unreasonable    nature    of 
t'K'  response,  its  sudden  reversal  by  certain  external 


5« 


Slii(Iii\s   ill  J  III  III  til  Ihhiiiior 


agents,  and  especially  the  fact  that  the  witless  crea- 
tures  continue   to   j^o   toward   the   \\g\\t  even   when 
they  are  brought  thereby  into  a   region  where   the 
heat   proves   fatal   to   them,   seem   to   bear   out   the 
conclusion   that  the  phototaxis  of  these   animals  is 
in  the  nature  of  an  involuntary  or  "forced"  response. 
'1  his  view  is  strengthened  by  the  results  of  certain 
experiments  on  individuals  which   were  blinded  on 
one  side.     These  experiments  were  undertaken  with 
the  \  '.•w  of  ascertaining  something  of  the  mechanism 
of  or.entation.     'Jhe  amphipods  do  not  become  ori- 
entetl  by  bending  the  body  toward  the  light,  but  by 
the  unequal  activity  of  the  appendages  on  the  two 
sides  of  the  body.      In   forms  with  positive  photo- 
taxis   it  was   found   that  blackening  over  one   eye 
caused  the  amphipod  to  perform  circus  movements 
toward  the  normal  side.      In  negatively  phototactic 
species  it  was  found  that  the  same  treatment  caused 
circus   movements    in    the    reverse    direction.      It   is 
probable    therefore    that   impulses    recei\ed   by   the 
eyes  cross  in  the  central  nervous  system  and  become 
carried  to  the  appendages  on  the  opposite  side  of 
the  botiy,  causing  them   to   act  with  greater  \igor, 
thus  bringing  the  animal  into  a  position  of  orienta- 
tion.     This   supposition   led   to   the   experiment   of 
cutting  the  brain   lengthwise  through  the  center  in 
se\eral  species  of  arthropods  and  it  was  found  that, 
although   sensitiveness   to   light  could  be   shown   to 
remain,   all   power  of  orientation  to  light  was   en- 
tirely destroyed. 


Traphms—RelatinH   to  Mndrs   of  lirhaiinr        59 

It  will  be  of  interest  in  this  eonnectlon  to  consider 
the  light  reactions  of  a  somewhat  more  hijrhly  or- 
pni/.ed    arthropoil,    the    water    scorpion     Ranatra 
1  h.s  insect  lives  near  the  banks  of  ponds  and  streams 
with  the  tip  of  its  long  breathing  tube  at  the  sur- 
face of  the  water  and  its  raptorial  fore  legs  held 
in  a  position  for  rapidly  seizing  any  small  passing 
creature  which  may  be  utilized   for   food.      When 
Hanatra  ,s  taken  out  of  the  water  it  generally  feigns 
death,  assuming  a  perfectly  rigid  attitude  which  it 
retains  through  all  sorts  of  maltreatment,  even  suf- 
fering Its  legs  to  be  cut  off  or  its  body  to  be  cut  in 
pieces  without  betraying  any  signs  of  animation.    By 
moving  a  light  over  the  motionless  insect  it  may  • 
gradually  be  brought  out  of  its  feint.     The  first  no- 
ticeable signs  of  awakening  are  very  slight  move- 
ments of  the  head  in  response  to  the  movements  of  • 
the  light.     When  the  light  is  passed  to  one  side  of 
the  body  the  head  is  rolled  over  ever  so  little  toward 
that  side.     Move  the   light  to  the  other  side  and 
the  head  tilts  over  slightly  in  that  direction.     Place 
the  light  in  front  of  the  body  and  the  head  bows 
down  in  front.     \ow  carry  the  light  behind  the  in- 
sect and  the  front  of  the  head  points  slightly  up- 
ward.     These  movements  occur  with  perfect  regu- 
larity in   response  to  the  movements  of  the  light 
and  gradually  increase  in  vigor  and  extent.     After 
following  the  movements  of  the   light  with  these 
definite  movements  of  the  head  the  insect  slowly  and 
awkwardly  raises  itself  up  and  begins  to  follow  the 


.S///(//(s   in   .Iniiual  litJiaiior 


h'^^n  witli  ri|ii;illy  liciiniti'  .s\\;iyiti^  niox  ciiicnts  of  ttic 
'""'v-  "  flit-'  ll^lu  is  ti)  oiu'  slilc  the  Ic^'s  oti  tli;it 
side  IMC  ll.AiiI  :iiul  the  oppnsiti.'  Ir^rs  (.•\tciulctl.  I'ass- 
iiiLj  (hf  llijit  ()\ir  the  IkkIn  tauso  the  rexcrsc  at- 
titinle.  I  l.il.i  the  li^^ht  in  front  of  the  hoiiy  ami 
the  insert  lious  down  in  front  in  an  attitiuic  of  ah- 
iea  siihinissioii.  Carry  the  li^ht  liehliul  the  inseet 
anJ  it  ele\ates  the  anterior  part  of  its  hoily  anil 
liiiKIs  its  lieail  hi^h  in  tlie  air.  These  hoilily  atti- 
tiules  are  assunuj  with  almost  niaehine-like  re^nilar- 
it\.  lor  eael)  isition  of  the  li^ht  there  is  a  cor- 
i\-poiulinir  position  of  the  head  ami  body. 

After  a  little  Ranatra  will  follow  the  movenients 
;'t  ihe  li;,rhr  hy  walkini^r  slowly  and  awkwardly  toward 
It,   t^radLK'Hy   increasinjr  the   vigor  and    rapidity   of 
Its  response  until  it  will  rush  toward  the  light  with 
tren/ied  haste.     It  becomes  oblivious  to  all  else  but 
tile  liglir.  which  seems  to  dominate  its  behavior  en- 
tirclv.     ll  the  source  of  light  gives  off  a  good  deal 
ot  heat  the  insect  will  continue  to  go  toward  it  until 
ovcrconie  by  the  heat.     I  ha\e  seen   Ranatras  when 
nearly  killed  by  the  heat  of  the  lamp  toward  which 
they  were  attracteil,  slowly  ilrawing  themselves  with 
the   last   rem-iants  of  their  strength   a  little  nearer 
to  the  fatal  source  of  light. 

X(<thing  could  seem  more  mechanical  or  more  ob- 
\  louslv  the  result  of  domination  by  outer  agencies 
than  the  phototaxis  of  this  form.  There  are,  how- 
c\er,    some    curious    features    of    the    behavior    of 


Kanalra   which   are   liisclosed  by  other   expert 


ments 


Trophms—Rclatio,,  m  M,„lrs  nf  Ihluninr 


r>i 


:i'ul  which  indicate  that  this  insect  is  something  more 
than  a  mere  "rellex  machine."     If  ..ne  eve  is  l,|.,ck- 
enej  over  there  is  a  strong;  tenderuv   lor  the  inse.t  . 
to    perf..-m   circus   movements   toward    the    normal 
side.      Ircqucntly  as  the   insect  veers  over  toward 
the  normal  side  in  Roing  towanl  the  light  and  thus 
I'nngs  the  unhlackened  eye  more  and  more  out  of 
the  region  of  direct  stimulation,  a  point  is  reached 
uhere  there  is  hesitation,  moving  this  way  and  that 
accompanied    hy    increasing    uneasiness    and    excite- 
n.ent  as  if  the   creature   were    exasperated   over  its 
predicament.     Sometimes    the  Insect    mav    get    out 
"f    this    situation    by   going    completelv    around    in 
a   circle   toward   the   normal   side,   or   it   mav   make 
a    direct    turn    f.ward    the    blackened    side    and   g.- 
toward    the    light.       In    several    cases    among    Ki- 
natras    and    Xotonectas    inilividuals    which    at    tirst 
performed     circus     movements     and     succeeded     in 
k^ning  to  the  light  by  a  very  irregular  route  finally 
came,  after  a  number  of  trials,  to  go  to  the  light 
'n   a   nearly  straight  line.      Other   individuals   went 
to  the  light  in  a  nearly  straight  line  from  the  first 
In  some  cases  covering  all  of  one  eye  and  all  but 
the  posterior  tace  of  the  other  did  not  prevent  the 
msect  from  going  in  a  nearly  straight  path  toward 
the  liglit.     Other  specimens  would  do  the  same  with 
only   a  small   part  of  the  lateral   face  of  one  eve 
uncovered.      In   the  latter  case   neither  the  lightest 
nor  the  darkest  part  of  the  visual  field  was  kept  be- 
fore  the   eye.     The   Insect  behaved  as   if  it   were 


62 


SiKilirs  in  .Immal  Bihav'wr 


not  piiidctl  by  a  mere   rclltx   response,  hut   had  an 
awareness  iil    the  general  space   rehitions  of   its   re- 
giofi,  the  rehitive  i)osition  of  the  li^rht  and  itself  and 
of   the  movements  nece-ssary  to  hrin^  itself  toward 
the   iiffht.      If   such    a    jfeneral   ti  poj^raphieal   sense 
seems  too  hifrh  a  psychical  endowment  to  he  cred- 
iteil  to  so  simple  a  creature,  it  must  Ik-  remembered 
that  other  insects,  notably  the  bees  and  wasps,  have 
a  much  nujre  ilefinite  ami  iletailei.1  coj^ni/ance  of  th.- 
topojrraphical    relations  of   their  einironment  than 
anything  in  the  behavior  of  Kaiiatra  would  call  for. 
Simple  and  niev!:anical  as  much  in  the  lij^ht  reactions 
of   Ranatra  seems  to  be,  there  are  many  features  of 
Its   phototaxis   which    are    very   ("itJicult   to    explain 
on  the  basis  of  simple  reHcx  orientation. 

We  might  expect  u  priori  to  find  that  somewhere 
in  the  course  of  evolution  the  tropisms  become  more 
or  less  subordinated  to  higher  forms  of  behavior. 
It   is   (juitc   eviilent   that   much   in   the   behavior   of 
'animals  may  be  explaineil  as  a  more  or  less  simple 
manifestation   of   phototaxis,    geotaxis,    chemotaxis, 
ami  so  on.     The  daily  depth  migrations  of  pelagic 
animals   is  traceable,   to   a   considerable   degree,   to 
variations  in  the  sense  of  the  response  to  light  ant! 
gravity.     One  circumstance  that  leads  copepods  to 
swim  to  the  surface   at  night    ami  go   down  in  the 
daytime   is  because  they  are  positive  to  wealc  light 
and   negative  to  strong  light.       The   negative   reac- 
tion ot  centipedes,  termites  and  many  other  organ- 
isms   kee()s    them    in    ilark    and    secluded    sit 


nations. 


Tropis,ns-R,luno„  ,.,  M„d,,   .,f  /i,,,^,,„^        ^^ 

'■''^-  P"sifivc  rcaai..ns  of  ,„anv  uunns  ;„ul  .,-.,>- 
t-u-ms  to  o.ntaa  stimuli  keep  then,  In  pn.tc.tol  . 
situations  n,  various  nooks  and  niche,  uhere  tluv 
-cape  many  of  their  enemies.  The  positive  ehe,n„- 
U  o  many  an.mas  leads  them  into  situations 
ufuie  they  may  tmd  their  food 

Hut  one  of  the  ehief  considerations  uhKh  makes 

stucl>oMrop,sms  of  such  importance  is, he  fact 
"  he  rropisms  enter  as  con.ponents  into  n.ore 
:;      Pl-  activities  of  higher  or^^anisms.      Tropisms 

He.rpunty  are  met  uith  only  in  the  simple    ani". 

s.     As  we  pass  up  the  scale  of  life  these  prima- 
uui  ncies   to   action    become    broken    up   and   c.  ,, 
>.ned  with  other  forms  of  behavior,  so  that  thev 

"H)  enter  as  comp(.ncnt  factors 

A  most  interesting  field  „f  investlKation  in  this  eon- 
""  H>n   .s  presented   in   the   relation  of  photot      , 

y   -e   n,vcs„,ator,    Kadi,   has   entered   upo 
"'"'   "">    ^"'""Miess.     There  seen.s  to  be  a  dose 
;,"■'""•""""■  "'"">■  ^"""als.  and  espeeiallv  in   „se        - 

etueen  photo.axis  and  „ha,  are  calledconn,     s   ' 
"  ry  n,ove,ncnts.     Place  a  lady-beetle  on  a  ,u        i  |e 
»  ..el,  ,s  slowly  rotated.    The  beetle  begins  to 
"     hea.l  and  then   its  body  opposite  the  directicn 
•....o™,ent.Kobber  flies  slnnv  the  reacti.X:: 
lall,    „cll.      Ihe   reaction   depends   upon   the  eves 
ec  use  ,t  no  longer  occurs  .hen  the  o'e.,  are  Hal. t 
0>er.     It  docs  not  depend  upon  the  rotation 


^4  Stinliis   in   .i.iniial   liiJimior 

of  the  insect's  ooJy.      If  the   insect  is  placed  in  a 
cyliml 


er  on  a  station. iry  center  and  the  cylinder 


ro- 


tated, the  insect  teniis  to  walk  around  in  the  direc- 


tion o 


f  rot 


ation 


A   f 


ro(r  under  the  same  circum- 


stances will  ilo  the  same  thiiiLr.      In  tl 


H'se  cases 


th( 


ar  as  possible,  /// 


amr7ial  reacts  so  as  to  keep,   so 
statu  quo  with  the  \isual  fieKl. 

A  heaiitiful  illustration  of  thi 
so-called   rheotropisin  of  lishes.      Many  fishes  ha\  e 
the  instinct  to  head  u|i  stream   ajjjainst  the  current. 


s  is  affortied  by  tht 


''"his  trait  has  1 


ieen  shown  by  Lyon  to  be  dependent 


upon  a  \isual  relle\. 


II( 


placed 


fish 


m  an  aquarium 


with  the  lower  side  made  of  t,dass  below  which  could 
be  drawn  a  lontx  piece  of  cloth  with  alternate  black 
and  white  stripes  on  it,  ^n\  injr  the  a|)[Harance  of  a 
moving  bottom.  As  the  stri()  was  pulled  alontr  the 
fish  swam  in  the  direction  of  mo\ement.  Re\ersing 
the  motion  causeil  the  lish  to  turn  about  and  swim 
to  the  other  emi  of  the  aciuarium.  In  another  ex- 
periment (ishes  were  placed  in  a  long  bottle.     When 


this  lloateil  il 


own  stream 


th. 


nslies  all  swam 


to  the 
the 


ream 


up  stream  ^nd.     When  it  was  pulleil  up  st 

fishes  all   swam   to  the   opposite   ^\u\.      I'i  hes   in   a 

stream,  [iassi\ely  carried  along,  ha\ 


e  no  means  ( 


be 


)f 


coming  aware  o 


fth 


eir  mo\  ements  exec 


ol   objects  m  their  he 


thi 


•Id  of 


pt  by 


means 


\ision  any  more 


th 


m  a 


man  in  a  balloon  who  is  carried  al 


ong  m  a  current 


of  air.     This 

relations   with    the    objects    in    their   field    of 


uitoinatic  tendency  to  keep  in  constant 


.•ei 


'S 


thi 


\  ision 


em     trom     neing    passively    carried    do 


wn 


srrc;un.      Many  insects  sIh.u   the  s;nMc  trait  in  tlu-ir 
I.vnR   a^ramst    a    h,v./c.      IV-rhaps    th.    instinct    „f 
'"•vcnn^r  sh.nvn  l,y  many  kinds  ..f  llics  is  an  expres- 
sion of  the  same  hnula.nental  tenJcncy. 

I  he   automatic  tendency   t..   keep   the   l,„dy   in   a 
ccrtam   onentati.m    to   its   held   u|    vision    ul.icl.    ue 
'"'Id    amcnK   crustaceans,    insects    and    lower    verte- 
i^'-ates,   ,s   to   a   greater  or   less   extent   replaced   in 
N.nns  wth  freely  movable  eyes  hy  ocular  nu.vemcnts 
uh.ch  enable  the  moving  animal  t<,  retain  the  same 
'-^■M  of  vision.      Stalk-eyed   crustaceans  show  com- 
IH'nsatory   movements   of   the   eye    stalks.      Similar 
eye  movements  occur  in  fishes,  amphibians  and  birds 
A  man   at  n.gbt  more  or  less  involuntarily  directs 
"IS  step     toward  a  single  light  in  his  horizon  much 
•>s  h.rds  .re  drawn  toward  a  lighthouse.     Such  ori- 
entation may  be  c,    scious  and  voluntar^^  but  it  can- 
n"t  be  denied  that  there  is  a  sort  of  instinctive  tcn- 
'iency  toward  it  much  as  there  is  in  all  of  us  a  strong 
tendency  toward  a  certain  orientation  t<,  the  force 
ot  gravity. 

The  reactions  of  animals  to  light  have  been  pro- 
•'Hnull^  modihed  by  the  evolution  of  the  image- 
l-rming  eye.  It  has  been  shown  by  Cole  that  if 
an  eyeless  form  such  as  an  earthworm  or  a  form 
with  simple  eyes  is  subjected  to  stimulation  by  t^vo 
sources  of  light  of  e.jual  intensity  but  of  '-.t-erent 
•M-ea,  the  animal  is  as  likely  to  turn  to  tf-  smaller 
"Sht  as  to  the  larger  one.  In  forms  with  image- 
•"nniiig  eyes,  on  the  other  hand,  it  is  the  light  of 


66 


Slmlics  ill  .hiiiiitil  Brhcnior 


lar^^rcr  area  whith  is  the  more  potent  in  causinjr  the 
furnin.i,'  of  the  body.     With  the  development  of  im- 
aire-torminiT    eyes    it    heeomes    possible    for    animals 
to    respond   to   objeets   atid   not   to   mere   differences 
II.  rile  amount  of  liirht  and  shatie.      {"he  imaj^e-form- 
uvj,  t\pe  of  eye  is  stimulateil  by  a  decrease  as  well 
as  by  an  increase  of  illumination  on  particular  parts 
ot    Its    surlace.       This    stimulation    is    jrcnerally    as- 
sociated   with    :iii    in\()Iuntary    turnin^r   towarti    the 
^ource  of  stimulation.      Hence,  the  automatic  turn- 
i!-.L^  of   t!ie  head  toward  a  new  object  in  the  (icld  of 
\Ision.    and   the   tendency   to    follow  the   mo\ements 
<d   botlies  with  movements  of  the  eyes.      The  eyes 
ot    annuals    are    notoriously    (]uick    to    respond    to 
movements.      The  movin^r  thing  is   the   stimulating 
tiling.      With    the    evolution   of   the   image-forming 
type  ot  eye  and  the  development  of  acute  sensitive- 
ness  to  change  of  illumination   of  particular  parts 
ot    the   retinal   surface,   the  general  tendency  to  go 
toward   or  away   from   light  may  pass   into   an   in- 
voluntary tenilency  to  becotiie  oriented  towani  par- 
ticular moving  objects  in  the  tield  of  vision.     When 
an   animal    reacts   in    a   definite   way  to   objects   im- 
pressed (in  its  retina  we  commonly' sav  that  it  sees, 
ihese    reactions   to   objects   come   to   be   very  com- 
!|K\  and  specialized.     They  come  to  depend  upon 
the  si/e.  form  and  color  of  the  moving  object.     But 
ir   is   not  improbable  that  they  have  their  primary 
n.ots    m    the    positive    and    negative   phototaxis    of 
simpler  organisms.     Josiah  Koyce  in  his  Outlines  of 


Tropisms — Relation  to  Modes  of  Behavior        67 

Psychology   has  gone   much   farther  than    I    should  . 
venture  to  do,  in  that  he  sees  in  the  tropisms  a  set  ,' 
of   tendencies   which    form    a    sort    of    fundamental  . 
background  e\  en  in  our  own  psychology.     Objects 
of  our   own    attention   exercise    a   compelling   force    • 
over  us  making  us  turn  toward  them.     We  involun- 
tarily turn   toward   a   person  or  thing  about  which    « 
we  are  curious;  in  fact  it  requires   some  voluntary 
effort  not  to  do   so.      Is   this  continual   orientation 
to  objects  akin  to  orientation  to  light,  odors,  etc..  in   • 
the  lower  animals?     According  to   Royce  these  re- 
actions   are    fundamentally    the    same.      Perhaps    if 
wc   should   follow   the   history   of   behavior   closely 
enough  in  passing  from  lower  to  higher  forms  we 
should  be  able  to  fill  in  the  intermediate  steps.     At 
present   the   connection    is   merely   a   suggestive    hy- 
pothesis. 

Most  of  the  work  on  tropisms  that  has  been  done 
thus  far  has  consisted  in  determining  the  precise 
way  in  which  tropisms  are  brought  about,  and  the 
conditions  by  which  they  are  modified.  To  find,  as  it 
were,  what  becomes  of  the  tropisms  in  the  course 
of  mental  evolution,  how  they  arc  converted  into 
higher  forms  of  behavior,  is  a  more  difficult  task. 
\  oltaire  has  made  the  remark  that  we  are  governed 
by  instinct  as  well  as  cats  and  goats.  It  is  possible 
that  we  may  be  justified  in  going  somewhat  farther 
than  the  celebrated  skeptic,  in  saying  that  to  a  cer- 
tain extent  we  are  governed  by  tropisms  as  well  as  . 
insects  and  worms. 


68 


Sliitlii's   ill   /Iniiiiii/   lUlunior 
KKIT'RFXCFS 


^  Hoiix.  Ci.  (i)  [.a  naissaiKc  dc  riiitclli^cncc, 
Pans,  1909;  (2)  La  iiouvclle  psychologic  animale, 
Paris,    191 1. 

CoLF,  L.  J.  An  experimental  study  of  the  im- 
age-forming power  of  various  types  of  eyes.  Proc. 
Am.  .Acad.  Arts  and  Sciences.  42,  335,  1907. 

Gkf,  W.  The  behavior  of  leeches  with  special 
reference  to  its  modifiability.  Univ.  of  Calif.  Pubs. 
>^ool.,    ri,    197,    \()i2. 

FIoLMKs,  S.  J.  (i)  Phototaxis  in  the  amphi- 
poda.  Am.  Jour.  Physiol.,  <;,  211.  i9(h;  (2)  'Ihe 
reactions  of  Kanatra  to  light.  Jour.  Comp.  Xeur. 
I'sych.,    15,  305,    1905. 

LoKH,  T  (i)  i^^^  Heliotropismus  dcr  Tiere 
und  seine  Uebereinsti.nmung  mit  dem  Heliotropis- 
mus der  I'Han/.en.  Wiirzburg.  1X90;  (2)  The 
mechanistic  conception  of  life.     Chicago.    19 12. 

I  AON,  I-:.  R  On  Rheotropism.  I,  Hheotropism 
in  iishes.     Am.  Jour.  Physiol.,   12.   149,   1904. 

Mast,  S.  O.  Light  and  the  behavior  of  organ- 
isms.    N.  v.,   191 1. 

Radi.,  I'",.  I  'ntersuchungen  fiber  den  Phototropis- 
nuis  der   Tiere.     Leipzig,   1903. 

RovcK,  J.    Outlines  of  Psychology.     N.  Y.,  1903. 

Wamiimkx,M.  F.    I  iie  animal  mind.  \.  Y..  1909 

\V(.i)si.i).M.,,K,  J.  j;.  F(,nnation  of  associations 
in  the  May-lly  nymphs  Heptagenia  interpunctata 
(Say),      (our.   Animal    Heha\  ior,  2,    i,    19 12. 


"^■"aaT.iUSit.; 


IV 


I  111.    I'KOI'.I.I.M    ol    OKIIMAIION 


TN  trcatiiijr  of  this  subject  one  is  compellcHl  to  cn- 
■*-tcr  a  iiclii  occupied  by  contcstinji^  parties.  The 
subject  ol  orientation  has  long  been  a  bone  of  con- 
tention, but  it  is  probable  that,  as  has  occurred  \n 
so  many  other  controversies,  a  deeper  insight  will 
result  from  the  conflict  of  opinion.  Allusion  has 
been  made  in  the  previous  chapter  to  the  theory  of 
orientation  to  light  and  other  forces,  which,  has 
been  developed  by  l.oeb  and  which  has  influenced 
so  largely  recent  work  In  the  behavior  of  lower  or- 
ganisms. This  theory  made  the  orientation  of  or- 
ganisms to  light,  heat,  chemicals,  etc.,  and  the  migra- 
tion of  animals  toward  or  away  from  the  source  of 
stimulus  an  entirely  involuntary  response  based  upon 
more  or  less  simple  reflex  action.  To  construe  be- 
havior in  terms  of  tropisms  and  to  explain  tro- 
pisms  as  the  ine\  itable  effect  of  reflex  action  which 
in  turn  was  supposed  to  be  determined  by  the  me- 
chanical and  chemical  constitution  of  the  organism 
formed  the  general  scheme  of  attack  upon  problems 
of  behavior  which  Loeb  and  his  adherents  have  at- 
tempted to  follow  out.  Many  features  of  the  be- 
havior of  lower  organisms  were  found  to  receive  a 

6y 


((> 


•V//,//V.s   /';/  .hiiiiidl  Btlunior 


very  pl;msil)lc  intrrptvtaticn  \n  accordance  with  this 
scheme. 

'I'iic  sMkIIcs  ui  Jcnninjrs  „„  the  hehavior  of  the 
siM.pI.r   animals   revealed   many   cases   of   apparent 
tropisms  to  which  the  tropism  scheme  of  Loch  did 
"<'t    applv.      Infiisorians   were    found    to   collect   in 
'•e'Kions  of  dilute  acid,   not  hecause   they  were  ori- 
ented to  the  lines  of  the  diffusin^r  suhstance,  hut  he- 
cause  when  they  accidentally  swam  into  the  rej^ion 
of   the  ddute  acid  they  remained  there.      'Ihe  col- 
lections thus   formed   were  the   result   of  a  sort  of 
selection    of    chance    movements.      The    organisms 
were  found  not  to  he  ahle  to  orient  themselves  at 
all,    although    the    aggregations    formed    resemhled 
those  which   ,n  other  organisms   are   the  result  of 
orientation. 

Although  the  formation  of  collections  hy  the  in- 
fusona  and  other  asymmetrical  organisms  may  occur 
without  (.nentation.  Jennings  helieves  that  in  sym- 
n-etrical  forms  in  which  the  hody  of  the  organism 
's   ohMously   oriented   to   the    stimulus   the   process 
^i"cs    not    occur    in    accordance    with    the    tropism 
scheme  of  Loch.      "In  the  symmetric:.!  Meta/oa," 
Me  says,     we  of  course  find  many  cases  in  which  the 
amnial  turns  directly  toward  or  away  from  a  source 
of    stimulation,   without  anything  in   the   nature   of 
preliminary  trial  movements.     'J'his  is  a  simple  fact 
of  observation,  which  leaves  open  the  possihilit^-  of 
nianv  different  explanations.     Is  the  simple  expla- 
nation gacn  hy  the  local  action  theory  of  tropisms 


The  Prnhlcm   nf  Orientation 


71 

'•nc  that  is  c,f  jr,,K.ral   applicahilitv  to  the  ciircctcd 
rcactK.Ms  of  lower  and  higher  Meta/oa?" 

'in  considcrinjr  the  evidence  on  this  .|uestion.  we 
Innl  that  even  in  the  symmetrical   Meta/oa  the  ch- 
'•e^tio.i    of    movement    with    reference    to    external 
ak^'nts  .s  by  no  means  always  hroujrht  about  hv  a 
Simple    direct  turning.     On   the  contrary,   in   many 
"f  the  Meta/oa.  trial  movements  are  as  noticeabb' 
and  miportant  as  in   the  Protozoa.     This  we  hax  e 
'llusrrated  in  detail   for  many  invertebrates  in  the 
section  devoted  to  this  subject   (Chapter  XII    Sec- 
tion 2).     I  or  such  behavior  the  local  action  theory 
"f  tropisms   fails  to  give  determining  facts" 

Just  how  Jennings  would  explain  orientation  such 
as  occurs  when  the  moth  flies  into  the  candle  he 
has  ncnvhere  made  clear,  further  than  saying  that 
ni  such  cases  the  organism  "reacts  as  a  whole"  in- 
stead  of  bemg  oriented  by  the  local  reactions  of  par- 
ticular  organs. 

That  the  orientation  of  a  symmetrical  organism 
-nay  be  largely  brought  about  by  the  indirect  method 
"f  a  sort  of  tnal  and  error  process  has  been  shown, 
•n   the   case   of   several   organisms,    by   the   present 
^^ntcr.      In  a  paper  on  the   "Selection  of   Random 
Movements^as  a  I- actor  in  Ph.totaxis"  I  have  shown 
hat  m  earthworms,  leeches  (Glossiphonia) ,  and  the 
■'  ;.^   <.     blow  H,es.  there  is  a   fairly  definite  orien- 
tation o»  the  body  to  light  rays  as  the  animals  move 
auay   from  the  source  of  illumination,  and  that  it 
's  n.>t  so  much  through  a  direct  turning  away  from 


72 


Si/iJi,.'.   ill  .liiiiudl  lUliinior 


the  lijrht  that  r.ricMtatioM  is  effected  as  by  the  cir- 
aimsrancc  that  all  nioveinents,   except  those  brinjr- 
iMK'  the  animal   away  fn,,,,  the  lijrht,   are  inhibited 
•T    revcrscii.      If  an   earthworm   is  placed  at    rijrht 
an^rK.s  ,,,  a  beam  ,,t"  litrht  "it  will  be  seen  that  the 
head  lre(iiiently  moves  from  side  to  side  before  ex- 
tension takes  place.     Tliese  movements  may  be  very 
shjrht  and  ordinarily  would  escape  attention.     There 
IS  often  a  similar  movement  durinj^r  the  process  of 
extension.     Fretiuently  the  head  is  bent  over  towards 
the  h^du  durin.ir  tlie  first  part  of  the  extension  and 
bent  the  oiher  way  and  extended  farther,  or  again 
It  may  be  waved  back  and  forth  several  times.   Slijrht 
trial    movements    in    all    directions    are    continually 
bem.tr  made.     The  reason  why  the  worm  makes  more 
turns  ot   a   decided   sort  away   from  the   Wght  than 
towards   ,t   IS   largely   because   the   little   trials   that 
brmg  the   worm  nearer  the  light  are  not  followed 
up.     Many  ot  the  turnings  that  would  naturally  be 
counted  as   negative  are  preceded  by  a  slight  posi- 
tive turn  followed  by  a  stn.nger  negative  one       In 
order  to  ascertam  whether  the  negative  reaction  was 
"Kuufested  at  the  very  beginning  of  the   response, 
the  foHowing  experiment  was  tried:      \  worm  was 
allowed  to   crawl   on   a   wet  board.      When   it  was 
crawling  ,n   a   straight  line   it  was   quickly  lowered 
"ito  the  bean,  from  a  projecti.Mi  lantern  so  that  its 
b<.dy  would  he  at  right  an-ies  t(.  the  rays.     The  ex- 
posure  to   the   light   was  made   in   each   case   when 
the   worm   was  contracted,   and  the   first  detectible 


I 


The  Prohinn   of  Oricitatiau  73 

"H.vcmcnt  of  the  head  to  one  sule  noted.      In  the 
two  specimens  employed  the  lirst  deieetihie  turn  was 
away  from  the  lif^ht  27  times  and  towards  the  liuht 
23    t.mes.      After   a    hs,   extensions    the   wonn    in 
near  y  all  cases  soon  turned  and  crawled  away  from 
the    light.       Ihe    first   detectibic   movement   (,f   the 
earthworm  seems,  therefore,  to  be  nearly  as  likely 
to  be  towards  the  light  as  away  from  it.    The  slight 
preponderance  of  negative  turns  ,nay  be  due  to  the 
<act  that  some  of  the  smaller  trial  movements  were 
"vcrlookcd,  to  a  slight  direct  orienting  effect  of  the 
rays,  or  merely  to  chance." 

In  the  leech  (dossophonia,  which  crawls  by  a  sort 
')t  loopmg  motion,  the  anteri.,r  part  of  the  body  is 
frequently  raised,  extended,  and  moved  about  as  if 
the  animal  were   feeling  its  way.     "If  the   animal 
turns  ,t  m  the  direction  of  a  strong  light  it  is  quickly 
withdrawn   and  extended  again,  usually  in  another 
direction       If  the  light  is  less   strong  it  waves  its 
head  back  and  forth  several  times  and  sets  it  down 
away  from  the  light;  then  the  caudal  end  is  brought 
forward,    the    anterior    end    extended    and    swayed 
about  and  set  down  still  farther  from  the  light  than 
before.      When    the   leech    becomes   negatively   ori- 
ented It  may  crawl  away   from  the  light,  like  the 
earthworm   m  a  nearly  straight  line.     The  extension, 
withdrawa    and  swaying  about  of  the  anterior  end 
of  the  body  enable  the  animal  to  locate  the  direc- 
tion  of   least  stimulation,   and   when    that  is    found 
't  begins  Its  regular  moscmcnts  of  lon.mr.tion      Of 


I 


74 


Stiidii.',   Ill  .hmthti  liiluiiior 


a  number  of  ramloin  tnovfrnciits  in  all  ilircctions  (.nly 
those  arc  foIlowcJ  up  uhich  hrin^  tlic  animal  out 
of  the  uniKsirahlc  situation." 

With  the   blow  lly  larva-  the  method  of  orienta- 
tion   was   mueh   the    same.      "When   a   stronjr  li^r|,t 
IS  thrown  on  a  lly  larva  from  in  front,  the  anterior 
enel  ot    the  ereature   is  drawn   hack,   turned  to  one 
Mde  and  extended  a^ain.     (  )ften  the  head  is  moved 
hack  and  l.)rth  several  times  before  it  is  set  down. 
I  hen  It  may  set  the   head  down  when  it  is  turned 
away  from  the  li;rl,t  and  pull  the  boily  around.     M 
the  head  in  movinjr  to  ami   fro  comes  into  stronjr 
hglit  It  is  often  retracted  and  then  extended  again 
in  some  other  direction,  or  it  may  be  swung  back 
without  being  withdrawn.     If  a  strong  light  is  thrown 
on  a   larva   irom   <.nc   side   it  may  swing  the   head 
cither    towards    or    away    fnmi    the    light.       If   the 
head   is   swung  towards  the   light,   it  may  be   with- 
drawn or  llexeil  in  the  opposite  direction,  or,  more 
rarely,  moved  towards  the  light  still  more.     If  it  is 
turned  away  from  the  light  '   e  larva  usually  f(,llows 
up   the   movement  by   locomotion.      Frequently   the 
larva    deviates   considerably   from    a   straight   path, 
but  as  It  continually  throws  t..e  anterior  end  of  the 
hody  about  and  most  frecjuently  follows  up  the  move- 
ment which  brings   it  away   fn  ~^   the  stimulus,    its 
general  direction   of  hjcomotion  is  away   from   the 
hght.      In  very  strong  illumination  the  extension  of 
the  anterior  part  of  the  body  away  from  the  light 
IS  lollowed  by  a  retraction,  since  in  whatever  direc- 


The   I'l'  hirm    nf  Ori,nt,ttinn 


75 


ti.n  It  may  cxniul  it  crii\i->,  a  sf-onj,'  stimulus  ami 
the  larva  writhes  aluuit  hclplessK  fnr  s<.mc  time. 
Sooner  ..p  hiter.  however,  it  follows  up  the  ri^r|,t 
movement.  Occasionally  the  larva  mav  crawl  for 
some  distance  directly  towards  the  li^rju,  but  after 
a  time  its  movements  irrv  it  in  the  opposite  direc- 
tion. When  once  iented,  the  direction  of  locomo- 
tion of  the  larva-  is  cor7i|)arati\  ely  straijrht." 

Ir    was    not    denied    that    these    different    forms 
sfiowed  a  c    tain  tendency  to  turn  directly  awav  from 
the  li;,rht.  hu'  it  was  contended  that  orientation  was 
tnainly  produced    "indirectly  by   following  up  those 
chance  movements  which  brin^  respite  from  the  stim- 
ulus."      I  he   li^rht   reactions   of   the    forms   studied 
"'nay  be  interpreted  as  a  resultant  of  two  motor  re- 
sponses;   first,    the    acti\ities    of    locomotion    which 
are  set  up  by  the  stimulus  of  the  light,  and  secoi 
the  act  of  jerkinjr  back  and  bending  the  body  from 
side   to  side  in  response  to  a   strong  stimulus   from 
iM   front.      Here  are  two  instincts  or  reflexes.     ,ow- 
e\er  we  may  be  pleased  to  call  them,  which  are  in 
a  measure  antagonistic  in  that  the  first  is  frequently 
overcome  by  the  second.     The  direction  of  the  ex- 
ternal stimulus  determines  which   of  these  two  in- 
stinctive  tendencies   predominates." 

'I"he  more  recent  work  of  ILirper  on  the  carth- 
u-orm  Prrich.rta  hermndcusis  has  shown  that  in 
strong  hght  the  worm  turns  away  from  the  stir.u- 
his.  but  that  in  weaker  light  "orientation  s  the  re- 
sult of  a   trial  and  error  method."     And   Mist  on 


l'< 


Slu,li,~  ill  .liiim.il  ll.lmih.r 


;■•';;■■  -".'i'>v„r,„,  \m„i„i„,,,i„„,,,  „,„,i„u,  „„, „,^.. 

,;,"";""   '■■""'".' 'o„,.,UH,  as  Holmes,  Harper 

;""'  •''"""":'■*  I'; -I  ""'•  "".I.M,l,to,lly  plays  a  v'-ry 

,'""■  I';!"  '"  ""=  "nc".a,i„„  „f  ,1,,  ,a,H,;v„r,n  ,Z 
•l.r  ".■;l,na,y  c„„,li, s."     T!,,  ,,,„„,  „,,„i„^.^| 

M.'^t  „,  IMS  „rc.|„l  st,„li„  „t  ,1,..   rcacti..„s  „f  Hy 

"'    y".l<MM  „„„.,„,,„.   ,„  iIr.s,   f„n„s  a,ul  a.l.l   a 
■""'■I'"   "f  "..crcs,i„«    facK   on.    „f   „,„,,    ;    '     ; 

>".-..l-al,l.c«c,„,li,v.,  larva- a,  lust  ;.,p,„J., 
;•""^-^^«lu...^,al,,,utaso, >.,,,,,„, ,,,/:;;" 

"""    ','    •""I   .TKn.a,;,,,,    Is    ,,(„,„!    ,„ainlv    In     he 

'-"■■"I  alu.v.  ,|.scril„.>l,  ,„„  „■..,-  lon^.r  -x  ,s  re 
upereenta,.    of  ,,,,,-,    ,,,„,s    ,>,„,,   ^he    li«h 

;--  'l-isaee.„„„„l,„rl,yMast,asMl,„s: 
l,e  larva-  are  eare/„lly.,l,serveJ,vlKn, hey  are 

nil.'-""'    "P    '■"'"""'   """--.liaeely 
""■>    II    t   e    anlen„r    en.l    Is    ,t,r„e.l    „,vvar.l    the 

-rca-  ,„   l,Kl,t  „he„  the  exposure  is  ,„ade.      1     thi 
"';'    '*    I"    -'"y    '"h"    P«iti.M,,    there    is    no    re 

the    lle-ht     ,,         I  ''  '"""   ""■"'■''   f™'" 

tIK    l,„ht    to    s,Kh    a„    extent    that    it    frem.entiv 

».»k«  a  n«ht  an„le  uith  the  posterior  en  J         -S 
!     ;;    "V„n«    haek.    I„,t    only    part    .av.      The      p 

--l-U"er,  exposed  and  so  the  aninKUmay  be  sti,"^ 


77/, •   I'rohlcm    uf  Oritut.illm,  j-j 

ulatcd  ajrain,  after  which  it  ajr;,i„  (u,„s  sharpiv  fn.iii 
the  source  of  lijr|,r.  This  process  is  repeated  until 
the  orRanisin  has  turned  to  such  an  extent  that  the 
anterior  end  is  practically  as  much  exposed  when  it 
turns  in  one  direction  as  when  it  turns  in  the  other. 
I  he  ^rrcat  prepomlerance  of  lateral  nioveinents 
from  the  source  of  li^rht  and  direct  orientation  in 
diffuse  h^ht  therefore  do  not  imlicate  that  lly  larva' 
have  the  power  of  dilferuifial  response  to  localized 
stimulation." 

l-oeh,    who    sets    little    store    hy    such    proximate 
catc-Kones  of  explanation  as  trial  and  error,  has  con- 
tended  af,^iinst  the   doctrine   that   orientation   is  ef- 
fected by  this  method.      In  speakin^r  „f  the  doctrine 
tliat  orientation  of  an  orjranism  in  stron^r  lijrht  may 
Ik-  direct,  while  in  weak  li^ht  it  may  take  place  hy 
the  indirect  method  described  above,  he  says:     "if 
the  photosensitiveness  of  the  animal  is  lessened  the 
ammal   may  deviate   for  a   lon^^er  period    from   the 
direction  of  the  li^rht  rays.     Such  animals  do  event- 
ually reach  the  lighted  side  of  the  vessel,  but  they 
no  lon^rcr  ^rc,  straight  toward  it,  movinjr  instead  in 
/ig-7.ag  lines  or  very  irregularly.     It  is  therefore  not 
a  case  of  qualitative,  but  of  a  quantitative,  ditterence 
m  the  behavior  of  heliotropic  animals  under  greater 
or  lesser  illumination,  and  it  is  therefore  erroneous 
to  assert  that  heliotropism  determines  the  movements 
of   animals  toward  the   source   of  light  only   under 
strong  illumination,  but  that  under  weaker  i'llumina- 
tion  an  essentially  different  condition  exists." 


?8 


StiiJic's  in  Jnimal  Bc/uniur 


Now  fhcrc  arc  undoubtedly  forms  to  which  Loch's 
remarks  arc  entirely  applicable.     The  possibility  of 
the  interpretation  which   Loeb  has  given  was  care- 
fully considered  by  the  present  writer  while  work- 
ing on  the   forms  above   described  and  was   finally 
rejected  as  inadeciuate  for  the  particular  cases  un- 
der consitieration.     It  was  pointed  out  that  "a  trop- 
ism  ol  the  direct  sort  is  not  necessarily  a  perfectly 
hxed  :uul   rigid  aflair.      It  may  be  a  tendency  more 
or    less    obscured    by    a    l..f    ,,f    random    movements 
nsmg  Irom  internal  causes.     An  organism  may  be 
drawn   to    a    certain    poin^   through    a    ilirect   orient- 
ing reflex,  but  if  ihere  is  at  the  same  time  a   large 
element  of    ranu.„n   activity  in   its  behavior  it  may 
seem    to    reach    that   point    by    the   method   of   trial 
ami  err(/r." 

A    careful    consideration    of    the    movements    of 
earthworms,  leeches  and  fly  larva-  made  it  evident 
that  orientation  does  not  take  place  by  the  method 
just  referred  to.      We  are  not  dealing  merelv  with 
the  masking  of  a  simple  tropism  by  a  lot  of  inconse- 
quential activity.     It  is  largely  by  virtue  of  and  not 
in   spite  ot    randcm   movements   that  orientation   is 
secured.      If  an  organism   were   so  constituted  that 
whenever    it    extended    toward    the    light    it    would 
jerk  back  and  turn  to  one  siiie,  e\  en  though  the  di- 
rcetion  of  its  turning  were  totally  indeterminate,   it 
would  finally  become  oriented  away  fr.;in  the  light. 
1  o  a  considerable  extent  the  reactions  of  the  forms 


rhc  Problem   nf  Oncntalinn 


79 


;t:::;^  ■■'■^■'''^■•''"^^■"'■^'■''-'>■>p■'''•--|-- 


•'■;    ..sy,M,„ctn«l   ,„   s,„„tM,x.   als...      M.,„y   f,,,,  , 

i.a.-.i.rc.c,,,,,,,,,,,,,,^Hv.,ui„;d,o„,  ,,,,.,,,,,:,,,„';., 

'-  1  ."..vc,„n,ts  >vlK.,u.vc,-  ,l,c  ,„,.;„■„„    „■  ,1,       : 
■'''';'"«"'•      "-■-'— .f  MKl,  lu-havi,,,.;' 

"'      '"":*    I"-: ■'    -,y    |.„Hn,lar    .h.orv   M        . 

i'"'':""^";  "',"-■"'»--     h  is  as  ..nsisL      „ 


"iiiaiK's   ofKf   SI 


""""'    •"•  thnnijrh    airi,.M-tv    ;is    K 

K-t-J.  as  ,t  ,s  >v,ch  the  rdlc-v  ,lK„rv.     Tlu.  I,„^r 

■""■"■'"'■'"^'""In-cft.cha,  -I,,,,.,'-,,,,.',,'; 

-  "'P"vr  an  ac,™  as  da-  .uu„„„.  ,n-  ,lK-\'     ' 

;;     ;.>.;«iK-MW.calfa™,.,f,^ 
I  '<-i<-u   as   the  outcome  ,,f    ,,mc   ulil-l,     ^      i     i 

'>    ^'-tcs    a    ccrtan,   prcsu.nprion,    anJ    o„c-     too 
\\nosc  strcn^rt  ,   \ari  s  .rn-ifK    ..  i- 

stances    in  I'm  *  •    •'^''"'''"•K  t"  cireinn- 

t'lnccs.  ,n  laxorof  any  -iven  conclusmn. 


8o 


Sliidiis   hi  Jitjwtil  lithdiinr 


Several   years   air,,   it   seemed   to   me   very   desir- 
able to  study  tropisms  with  the  view  of  testing  the 
possible    presence    of    anv    more    highly    developed 
functions  than  are  postulated  by  the   reflex  theory. 
I'or  some  reason  this  particular  (luest.  which  invohes 
one  of  the  most  imjiortaiit  theoretical  considerations 
connected  with  the  tropism  theory,  had  been  almost 
completely    neglected.       I    have    alread.    alluded    to 
some  of  the   initial    experiments   which' consisted   in 
blacking  over  on,.  ,,f    the  eyes  in   several  phototac- 
tic  species   of  arthroMo.ls  and  then   o!)ser\  ing  their 
reactions    to    light    under    various   conditions   of   ex- 
posure.     It  was  f.uind  thai  in  several  positively  pho- 
totactic  species  blinding  oiic  eye  tended  to  make  the 
animal  perform   circus   movements  toward  the  nor- 
''j:'l    side.       In    several    negative    species    similarly 
blinded,   circus   movements   were    performed    in    the 
reverse   direction.       ihis   is   what  the   reflex  theory 
of  tropisms  would  lead  us  to  expect.      Jhat  the  re- 
lations discoxered    are   fairlv  general   is   evinced  by 
the  discovery  by  other  investigators  as  well   as  by 
myself  of  a   number  of  other  forms  which  react  in 
a  similar  manner,      (ireat  individual   variation   was 
found  in  the  degree  to  which   the  tendency  to  per- 
f«)nn  circus  movements  was  manifested,  some  forms 
alter   being  blinded   on     uie   side   continuing   to   go 
toward  or  away  from  the  light  in  a   nearly  straight 
line.      I  he   fact  observed  bv    mvself  in   Ranatra  and 
Nor.mecta    and   subsequently    found   by    .Miss    JJrun- 
clni  m  Orchestia,  that  individuals  which  at  first  per- 


The   Prohltm    „f  (Jrinihiti,ni 


8i 


l-nnccl  cu-cus-  nu,vcn,cnts  later  a.,„c  t..  u„  tcuard 
'''-■I'Kl.t  in  a  ncarh   >traiKlit  uuirsc,  iiulia.tcs  a  ca- 
P-H-Ity  h.r  .Tuulati.u,  in  hc-lun  i.„-  if  not  a  priniitivc 
';••■'"  "'    icarnnij^r,    and  swK^csts  the   |,<.ssi!v.cv  that 
tl'c  normal  tropisnis  of  these  forn.s  are  not  wholly  a 
".atter  of  d.reet  retlex  action.     Were  these  ani.nals 
inirc  reflex  nieehanisn:s  we  shoiiKl  expect  their  cir- 
U.S  n.oven.ents  to  co;  tinue.     Hut  jud^nnf;  fn.„.  their 
behavior,    these   aninnls   follow   li^rht  more   or  less 
alter   the   .nanner  in   which   hijrhcr  animals   pursue 
rhe.r  prey  or  any  other  object  of  interest.      Possibly 
the  same  may  be  true  of  the  (iddler  crabs  which  move 
suewise  toward  the  li,uht  instead  of  orientin^r  them- 
selves m   the   usual   manner  with   their  lon^mudinal 
axis  parallel   to  the   rays.      I.,eb  is  inclined  to  the 
^""dusion  that  -in  the  fiddler  crabs  in  the  first  place 
there  IS  an  entirely  diflerent  connection  between  the 
'ct.na  and  the  locomotor  muscles  fr.nn  that  in  other 
erustuceans,   and   that,   secondly,   there   is   a   special 
Pecuhanty  in  regard  to  the  functi(M,  of  the  two  re- 
•"i^^'  ^;'^^''-^'l'vH.ey  do  not  act  like  symmetrical  sur- 
'■uc  dements         In  the  li«ht  of  the  facts  .Mentioned 
■'I'nve  ,t  ,s.  [  beheve,  doubtful  if  we  nc.d  to  assume 
any  far-rcachmjT  modifications  of  nervous  structure 
">    account    for   the    peculiar   orientation    of    these 
^'al)s.      J  his  rondusion  is  supported,  I  think,  by  the 
:  vi'enments  of  Miss  Hrundin  on  Onhrslia  Inukiaua 
•"  uhich  the  amphip<,ds  which  have  a  narn,w  im- 
pressed body  were  compel!:d  to  travel  on  one  side 
l'>    being    confined    betweer-    two    hori/<,ntal    gla. 


iss 


S2 


S  Indies    III    ./ Ill  nidi   nrlhiii(f 


pl;'tis.       Mtliouirh  (.riciitatioii   ii,   the  umi:!!   wav  uas 
I'DpHssibk..   thr   ainphipruls   niuvcl   towar.l   rlu'   lijrhr 
In    push,,,-  against  the  ^las.  uirli  tlulr  Ic.^s  and'hy 
"cM„;,r  a,u|  cxfculin-  tiK'  l>,ulv.      Tiic  Inn^r  axis  was 
kept    l^..,titc>l    app,-,.xi,„atrl\    rnuard    the    lijr|,r.    \,^^^ 
tins    p.-sitinn    was    inaintal.uJ    l>v    nunamnts    quite 
'lilt''ivnr    tn.,n    those   i,nnlveJ    in   ..nuitari-.n    under 
'"""'•'1    n.n.l,r,.,ns.       Sinee    the    photntaxis    n{    this 
speues  IS  .vadilv  n„.JIl,ccl  !n   experience  it  is  n..t  i,n- 
P'-'.lKihle  that  s.unethin^r  „„„-,.  than  direet  reflex  ac- 
tion   ,s   ,n^n!ved.      IV.'haps   the   exph.natlnn   of   whv 
•'"i-nals  dn  the  things  that  rhev  hke  t..  d<.  is  involved 

Ml  '"'v  e..,nplete  acer.unt  nf  the  ..rientatinn  nt  higher 
forms. 

'••;••  ^^^orc  primitive  types  in  which  behavior  is  Tt- 
'1^'   "    :-t    all    ,nodif,ed   throujrh    the   :x^aKy   of   asso- 
ciative nuinorv  there  is  no  reason  for  douhtin^r  that 
orientation  ,s  ctteeted  hv  means  of  retlex  action      Hut 
^rant,,-^  this  to  he  true  there  is  roo,n  for  a   va.aetv 
<d  wavs  ,n  which  orientation  uKn  he  ln-ou,L,dit  about 
Alanv    annnals    respond    verv    readily    t..    a    sudden 
jl-a-me    ,M    th.    intensitv    of    h-ht.    while    thev    show 
little  or  no  .vsponsc  when  exposed  to  constant  ilhnni- 
"^'fon.      In    sonu-   cases   a    sudden    increase   of   li.rht 
intensitv    pn.duces    a    rea   tion.    but  tnore    f,-e.,uentlv 

the  .-esponse  ,^  evoked  wh<.  the  ituensitv  of  the  lijrhr 
>s     dimimshed.        Hun.^rv     '.eches      ( ( ih.ssiphonia ) 
'T'   "'^   y^'i/^t^'-ul    the   ant.,;or  end   of  the   bodv 
jvhen    a    shadow    passes    over    them,    a^d    -nosquito 
'•"■^■i'    ^vrig^Ic    downward    under   the    ^am.^    cln-um- 


I 


The  Probhm   of  OnniUiiunt 


83 


stances.      \ovv   ,  riranisms  of  aiiv  kiiul   in  ^rnln-r  t,, 
"•:  ;'-'|ni  th.  Hjrhr  arc  subjected  ,.,  irc.]ucnt  Juin^r,, 
"t   I>Kht  uucnsirv  as  they  deviate  n.  ,.ne  siJe  ..r  the 
-ther  <.t   their  course.      Do  the  fluctuations  of  li^rht 
mtensits    so  c  lused  produce  stimulations  that   attect 
tlu-  orientation  o'  the      unialr     The  possihih'tv  that 
sti.nulations  produced  by  such  fluctuations  in  the  in- 
tensity ot  ii^rht  ini^rht  plav  a  nMe  in  orientation  was 
siii^M^^ested  in   my  paper  on  the  phototaxis  of   Rana- 
"■'i.      \s  this  insect,  uhen  one  eye  is  blackened  over. 
ncNcrthe.ess,   in  some  .ascs  «oes  nearlv  straight   to 
'I"    Hht,   .t   was  pointed  out  that   -were  the  insect 
M.  constituted  as  to  respond  to  an  increase  of  jij^rht 
^nteruiK  the  left  eye  by  a  turn  to  the  left  and  to  a 
decrease    of   Jijrht   by    a    turn    to    tlie    rijrht.    we    can 
understand  how.  when  once  pointed  to  the  li^ht    a 
^ri-ai«ht   course  mi^ht   be   preserved.      If  the   insect 
u-ned    towards    the    riirhr    there    would    be    an    in- 
ucase  of  h^ht  enterin^r  the  left  eye  which  ue  mi.dit 
suppose  sMmulates  the  insect  to  turn  in  the  oi.posite 
'hrection.       Deviations    to    the    left    would    cause    a 
^liminut.on  oi   Jijrht  entcrinjr  the  left  eve.   which  we 
un-ht  suppose  acts  as  a  stimulus  to  turn  to  the  ri- 
■^i^lc.       I  he  ri.irht  eye  may  be  suf.posed   t..   au.    m 
lulls   wHlaiidi,,  in  a  similar  manner." 

il!c  conclusion  reached,  houevcr.  was  r  ,  .t  re 
N-nses  to  fluctuations  of  li^ht  intcusltv  alone  did 
"-t  Kive  an  ade.,uate  explanation  of  the  orientation 
"'  tfus  lorm.  although  thev  miirju  afford  a  co- 
"Pu-ative  factor.     Such   responses  proba!,K    do  plav 


riL^nt 
mil- 


84 


SliiJirs   ill   ./ni  III  ill   [ivluninr 


:>"  important  r.M..  i,,  ,„•.., h.dn.i;  timsc  ..ricnti.ijr  hk.vc- 
iHctUs    kn.nvn    as    ounpuisaton    motions    where    the 
l^'ttcT  are,   as   in    nianv   insects,   dependent   upon  the 
'H-k'ans  of  ,„;,.„.     Mast,  who  is  an  opponent  of  the 
view  that  phototaxis  is  the  result  of  Hfrht  actin^r  as 
a  constant  stnnuhis.   is  inehned  t..  attribute  orienta- 
tion very  hir^elv  to  intensitv  .han^es.      In  speaking 
"<   orientation  in  >nany  hnver   forms,   he  says:      "In 
"lany  of  these  fonns  orientation  is  undouhtecllv,  and 
.'"   ^'Il't   IS  probahlv,  a    response  to  ehan^r,  of  li.rht 
intensity   on   sr.mc   part   <.f  the   organism.      At   any 
rate   it   has   m   no   instance  been   demonstrated   that 
It  IS.  as  I.oeb  states,  'a  function  of  constant  intensitv  ' 
that  orientation  to  li^rht  is  hke  orientation  to  an  elec- 
trie  current.        There  is  much.    I   beheve.   that  indi- 
cates   that    hfrht    stimulates    .juite    apart    from    the 
shoeks    due    to    variations    in    its    intensity,    but    the 
•lucstion  as  to  the  relati^e  potency  of  the  two  factors 
'"volved,   which    Mast  has  done   well   to  brin«  into 
greater   prominence,    is   one   that   can    be    answered 
only  by  experiment.     In  the  ordinary  movements  of 
animals   to   and    from   the   lijrhc   both    these    factors 
are     ree  to   n.me   int.,   play.      The   natural   method 
of  attackiniT  tne   problem,   therefore,    is   to   exclude 
one  of    the   possible   agencies,    and   then   to   observe 
the  etteet  ot  the  other  alone, 

Recently  a   series  of  experiments   was  carried  on 

•n  ^''^;^'y;'au  and  myself,  in  which  animals  were 
c'xt'osed  to  illumination  which  was  rendered  constant 
-   lar  as  this  could  be  done   in   the  case  of  an  ac- 


Thf  Pmbhm   nf  Or'uutatiiin 


85 


tnely  moving  animal.      In  one  set  of  experiments 
'  K-  >nsect   was  placed  in   a   jar  lined  below  and  at 
tlic  sides  with  white  paper.      "This  was  covered  by 
.1  n.ne  of  the  same  material  in  the  apex  of  wt.Vh 
was   placed   an   electric   li^Wu.      A   small    peep    hole 
permitted  the  observation  of  the  insects  in  the  jar 
IM   several   experiments   the   insect  was  placed  in   a 
small   circular  ;,dass   dish   in    the   center  of  the   en- 
closure.     Whether   the   insect   turned   to   the    ri^'ht 
'"•  to  the  left  in  this  apparatus  the  amount  of  li^rht 
enteruifr  the  eyes  was  approximately  the  same      In- 
sects with   one   eye  blackened  over  were   placed   in 
the  jar   and   stimulated   to   activity   whenever  they 
;;""e   to  rest  by  tappinjr  on   the  jar,   or  when  this 
failed  by  poking  them  with  a  wire.     ']-he  very  slight 
variations  in  the  light  entering  the  eve  in  the  dif- 
ferent positions  of  the  insect  w<,uld  have  different 
ciiects,   according  to  the  theory  of  differential  sen- 
sil^ihty,  depending  on  the  position  of  the  insect,  and 
^;"'ild  m,t  tend  to  produce  a  constant  deviation  of 
the  path  m  any  particular  direction.    The  same  may 
be  said  ot  variations  caused  by  movements  out  of 
the  horizontal  plane.     Since  the  slight  effects  of  dif- 
ferential sensibility  would  tend  to  neutralize  one  an- 
«»ther,  any  uniformly  directed  movements  may  be  at- 
'nlnited,  with  considerable  probability,  to  the  con- 
stant stimulating  effect  of  the  light." 

Several  negatively  phototactic  beetles  placed  in 
Mie  apparatus  showed  a  general  tendency  t.,  turn 
fnvard    the    blackened   eye.      A   Jerusalem    cricket, 


sr, 


Sliuli,'.    in   .hiiiiiiil   Hthaiiof 


SrcM(.iH'I.n;.tus.  u  liicl,  is  rufratiy  c  to  li^rht.  was  plaanl 
I'l  tiic  uu-|„surc  after  \r,xv\n^  its  left  cvc  hiackuud 
"\ei-.  Wli.n  cn.ssin^r  the  nKlosurc  it  inxariahly 
'J-nud  to  the  left  and  enntinueJ  to  ^n  an.u.nl  in 
tliat  direction  when  it  came  in  contact  with  the  edjrc 
S'^Ncral  flies  showed  very  decided  circus  nin\  ements 
•."^^■^"■''  ''"-•  ""ni.al  sl.le.  Thus  even  under  condi- 
""■'>s  Hi  practically  continuous  stimulation  these 
'"'■ins  kept  up  their  orientin^r  activities. 

'n  another  set  of  experiments  insects  were  held 
I"  a  'iNyd  position  while  their  ettorts  at  locomotion 
uere  ^iven  opportunity  for  expression  hv  rotatinir 
a  Hnn/ontal  disk  mounted  on  a  pivot  like  the  turn- 
table ol  the  microscopist.  '•The  apparatus  was  made 
\^'>v  li^ht  and  easy  runnin-  so  that  even  a  small 
insect  could  set  it  in  motion.  \U  holding  an  insect 
mer  the  disk  with  the  head  pointing  either  toward 
">•  auay  from  the  center,  and  havin^^  a  li^du  so  that 

tlu-  ravs  fell  on  one  side  of  the  hodv,  the  movements 
<•'  tlH'  Ic-s  which  would  ordinarilv  turn  the  insect 
"'^^^'.'•^'  ;''e  li.i^du  would  simply  cause  the  disk  to  ro- 
tatein  the  opposite  direction.  Wirh  the  insect  held 
steadily,  the  stimulus  att-n-ded  hv  the  li^ht  would 
natural!)  rem.on  constant,  and  if  li^rfu  oriented  hv 
-rs  constant  stimulatin^r  effect  we  mi^dit  expect  that 
tlK'  insect  would  keep  rotatin-  the  disk  in  its  at- 
tempts  at  orientation. 

'•HutterHiespnacd  tohevei-vconvem.nttn  work 
^^-  ••  '"-^v  In-  -raspin- them  In  rhc  win-s  fold..!  to- 
Kcther    above    the    body    thev    could    he    held    quite 


Thr   Pmhlrm    of  Orirm,ili 


nil 


87 


au 


InC 


a  liaihl  rest,  ahov  c 


stcailil\,  rspciially  with  flu 

tlu'  disk.      \  cabhafrc  Imrtci- 

laciii^r  the  center  of  tlie  tlisk  ami  presentin-^  its  ri;,'lit 

sliie  fo  the  li^ht.      Almost 


/(■/V 


//>, 


/■,  was  lielil 


ted  t( 


mimeiliatelv  tlu    Initterlli 


turn  fouani  the  li^ht.  and  li\    tl 


le   ae- 


atteinp 

tl""  of  its   leys  caused  the  ilisk  to  rotate  in   the  op- 
posite direction.      \tter  a  tew  rotations  of  the  wheel 

e    reverse    position 


the   hutterlly    was    turned    into    th 


that 


Its  jelt  siclc  was  e\|)osed  to  the  liy[ 


It. 


a   lew  seconds  ir  lu7,Mn  to  turn  the  disk 


Witl 


iin 


tlu'  liirfit  as  he  tore 


w 


away   Iro-n 

if:n   rejdaceii  in  its  orii,nnal 

a;,Min  towar>" 


position  the  hutterlly  rotated  the  disk 
the  letr  side.     Several  suhse(]ucnt  trials  ya\c  similar 

U'    same   species 
e   saiiu'   uav   as  the   oiu- 


results,    and   another  specinuti   of   tl 


respomlci 
dcscrihed 


in 


practically   th 


•I- 


xperinu'nts  with  Mrlii^ru  cluilnd 


on 


\ci-y    similar   to    tho,,e    with    the    cabhaye    1 
the  insect   was  held  jioinrinjr  o!ili,ji,i.>| 
t'l-om    the    liyhr   it    wouKi    sti 


W 


f^a\e  results 


nitrertlv. 


M:n 


\    awav 


Ir 


on 


turn    the    di-k 


n    tfU'    more    illunnnatcil    sid*. 


W 


awav 
un    p(unti.iL>; 


'hli(]uely  towar.l  the  li^rh,  the  hutterlly  would 


the   same    response.      I 


n    which    the   hoil 


n   e\ery   position   except   that 


ere  efforts  to  turn  t( 


y   was   parallel    to   the    ravs   th 


ere 


in 


the  rotation  of  the  clisk.      If  th 


Avarcl  the  liyht.  which  resulted 


tacin<r  the  liirju,   rotarv 


e  insect  was  held 


moNcinents  uer 


I    conse(iuence  of    attempts   at    forward   I 


c'  set  u[)  as 


ocomotion. 


he  rotatetl  for 


In  many  cases  the  liisk  would 

minutes   without   cessation,    and   when   the   huttcrfiy 


several 


ss 


SiiiJi.s  in  Jniinal  lichinior 


'n-ca„u-  .|mct  it  ou,M  KcncTallv  he  caused  t..  resume 
"•>    .H^mity    l.v    pull.n^r   it    sli^rfulv    h.-ukuarJs.       In 

''••^  '^ns  a,ui  M.Iira-a  the  head  u as  kept  turned 
sI.Khtly  tou.nd  the  h«ht.  l-„ry„n.  rnruhnnr  and 
(■<>,„  „y,„ru,  ,al,fnn,„.  ;,lso  rotated  the  disk  away 
"•"".  the  h.uht.  Most  ..(-  the  specimens  of  A^J 
"'•vw/  a„l,n[u,  experimented  with  failed  to  j^ive  re- 
sults on  aeeount  of  fci^rnin^r  J,,fh  s..  lon^r  as  they 
^v^--c  held  hut  one  indisidual  heeame  aetive  after 
i'  tin.,  ;n,d  consistently  rotated  the  disk  aw.iy  fr,„n 
tlH-  illummated  side. 

••■'■vvo  species  of  Diptcra  of  the  family    1  aehinid.r 
'■••t-'ted    the    d.sk    uniforndv    away    fron,    the    h^ht. 
'>ther  specnnens  when   held   wouM  execute  only   ir- 
rcKuhu-  mo^ements.     The  same  was  true  of  several 
other  phototactic  Insects  heh,n«ing  to  different  or- 
;  tTs.      1  he  aculeate  1  ly.nenoptera  expended  most  of 
thc.r   energy   m   efforts   to    stinj.^   their   captor;   and 
atten.pts   to   escape   in   most  other  cases  effectually 
overcame  any  phototactic  proclivity  that  may  have 
existed.      lloweNcr.    the   comparati^  ely   few   insects 
tl-a'   continued   to  exhihit  h^ht  reactions  under  the 
'■"natural  condition  of  hein.^  held  bet^veen  the  fin- 
K^rs  or  by  forceps  ^^a^c•  such  uniform  and  unecjuivo- 
J;'     reactions   that   there    can    he    little    doubt    that 
li^'ht    exercised    a  continuous    stimulating    influence 
^'P-  the:  r  activity.     The  slight  movements  due  to 
;;"^'  ^  '-and  or  the  insect's  own  actions  would  affect 
;   't   very   httle   the   amount   of  stimulation    received 
'^y  the  eye,  and  whatever  effects  would  be  produced 


MICROCOPY    RESOLUTION    TEST    CHART 
ANSI  ond  ISO  TEST  CHART  No    7 


1.0 


I.I 


I:  «^ 

'-         |40 


iiiia 
11= 

mil  2.0 


.8 


1.25 


1.4 


1.6 


^     .^IFPLJEn   iM.^GE 


V" 


StiiJh}   ill   .hiinuil   lliluiii'ir 


^\""''I  '"akc  it   evident  that  li^^ht  acts  as  a  constant 
:""'"'"'^-      '  '"'^  '''^v,  acconlin-  tu  uhich  plint..dicin- 
lyal  c!tc^t^  arc   prnporri.uial  t.i  the  intciiMtv  of  li.rhr 
Ji"ics  ,ts  chiration,  has  been  shoun  hv   Bhiauu-  a'^i.l 
l>.\    I  roschc'l  to  appiv  t<.  the  pliototropic  henJin^rs  ,,t 
;>^'vcral    plants,    an.l    I  ueh    an.l    luaKl    have    shoun 
■'^  .'IM  Ii-it:on  to  similar  curvatin-e>  of  the  hvch-nlj 
'nde/ninuni.       As    vet    the    rehttion    ot"    this    huv    to 
pl>"t-taMs  ,n  anin.als  has  been  httle  stiaheJ,  ouin.i; 
■■"-.uelv  t..   the   practical   chtHcnlties   of  puttin^r  it  („ 
tl'c  test.      Inasmuch   as    hjrht    is   s„pposeJ   to   stimu- 
'•><^'  l\v  Mrtne  of   the  chentical  cl,a,ij,res  it  induces  in 
the  sensorv  orirans  ,„•  surfaces  of  the  organism  one 
wouKI   scarcely  expect  to   (,n.l  so  general   a    function 
;is   orientation   dependent  merelv   on   the   stimuh    af- 
^'^y^\^-d  hv   Ihictuations  of  hj^rhr  intensitv.      Certainlv 
IiRht    exercises    a    fairly    constant    stinudatin-   etiect 
"1-"   our  oun   cNes.   and   ,t   is   verv  prohahle  that   it 
a^ts  ,n  much  the  same  way  in  the  h.uer  animals 


Kii  i:ri:\ci;s 

Han(K..ii,I-.\V.      Ilcdiotropism.dilterentialsen- 
sjhditv.  and  ^ah  anotropism  in  luj^dena.      four,  l-xp 
/ool.    1  :;.  ;,S  ^.    |,^|^. 

'^'«  ^"1^.  M.  T.  Il.ht  reactions  of  terrestrial 
•'"M'l"pods.      |.,ur.   Animal  Heha\i(,r,    ^    ^44.    1,^,  . 

llM^'-'K.  I-.  II.  Reactions  to  ii^rht'and  niechani- 
'a  M.muh  ,n  the  earthworm  IVricha'ta  hermudensis 
(I^^'hlard).      Biol.   Hull.    IM,    ,7,    ,,,,,- 


Rtftrcumi 


91 


IlolMis,  S.  J.  (I)  l'lii.r()t;i\is  in  the  Xmplii- 
I'lulii.  Ami.  Jmir.  I'lissinl.  ;,  :ii,  1 1;' >  1  :  '2)  I  lu' 
M.-K-i.ti()ii  (it  raiulorn  iiios  ciiKiits  as  a  Lutor  in  phu- 
t(ita\is.  jdiir.  Co. lip.  Ncur.  I\\i.!i.  1;,  (;S.  i'>'';; 
{  \)  I  he  reactions  ot  Kanatra  to  h^ht.  I.e.  1^,  V'^- 
I'y;:  f.)  )  the  [>liotota\is  ol  luliller  erahs  ami  its 
rehition  to  theories  ot  orientation.  1.  e.  iS.  4(>;?, 
i';"S:  '^)  I  he  e\()hition  ol  animal  intellii^eiue.  N. 
^  ..  I ';  I  I  :  ( '') )  l'hotota\is  In  the  sea  tirJiin,  \rha- 
iia  punctulara.  Jour.  Animal  Heha\ior,  1.  \i(), 
I  <;  I  2 . 

IIoIMIs,  S.  J.,  anvl  Mi(iK\\\.  K.  W.  Some  e\- 
|>eriments  on  the  methoil  ot  orientation  to  light. 
J<iur.  Animal  Uehavior.  ;?.  },()~,    i '>  i  v 

jl.NMVcs,  II.  S.  I  he  heha\ior  ot  lower  organ- 
isms.     N.    \  .,    I  (y<  )6. 

Loi.li,  J.  (  I  )  Stiulies  in  general  [)livsiologv, 
Chicago,  1905:  (2)  Dvtiamies  ot'  li\ing  matter,  \. 
'\  .,  I'yo^;  (^)  I  he  meehanistie  eoneeption  ot  lite, 
\.   \ .,    1912. 

I.<il  1;.  J.,  and  I'wM.n.  W.  I''.  leher  die  (iultig- 
kcit  cies  BuMsen-koscoeselicn  (ieset/es  tiir  ilie  helio- 
tropisehe  I'.rschcinung  hei  I'icreii.  /crit.  f.  I'hvsiol. 
27.   I  165,   1914. 

M\sl,  S.  <).  l.iglit  and  the  behaxior  of  organ- 
isms. N.  '\'.,   191  1 . 

I'm  II  \.  H.  M.  A  (|uantitati\  e  determliiati.in  of 
the  orienting  reaction  ot  the  hlou  t!\  l.nxa  '  C  alli- 
pliora  er\  throce[)lia!a  Meigen  )  .  Jour.  I'.xp.  /ool. 
17,  213,   1914. 


92 


Stiidirs  ill  .tiiiiiiiil  fhJuninr 


''"•"-•^•1  V.  H.  [}.  I  \)  Tlu'  inctlioj  of'  trial  and 
the  trojiisiii  hy[><>tln.sis.  Sticncc  \.  S.  26,  -ji^, 
i<)< >-/-,(  2)    I  rials  anil  tropisiiis.  1.  c.  jjy,  S73,  191  3. 

Wasiiiukn,  M.  I-.  The  animal"  mind,"  \.  Y., 
I  909. 


Tin.    Kl  \I.KS\I.    OI      IKulMSMS 


/^NI'.  \cry  prcsaktit  ami  noteworthy  pcmliarity 
^^ot  the  tropic  movements  of  animals  anil  plants 
is  the  phenomenon  ot  reversal.  The  same  organ- 
ism fTiay  show  a  positive  or  a  neu;ative  reaction  to 
temperature,  li^ht,  i^ravity  or  the  electric  current 
according  to  the  strength  of  the  stimulus,  the  or- 
ganism's own  condition  or  the  coincident  intUience 
ot  other  agencies.  I  hroiigli  this  [lovvcr  ol  reversal 
behavior  is  renderei!  more  plastic,  (iranting  that 
tlie  tropisms  are  involuntary  reactions  to  external 
stimuli,  the  fact  that  the  organism  may  go  either 
toward  or  away  from  a  stimulus  acconling  to  !)ovv 
it  is  inHuenced  by  various  internal  and  external  con- 
ditions iiKiKes  its  behavior  much  more  varied,  atui 
affords  an  opportunity  for  a  closer  adaptation  to 
the  numerous  environmental  agencies  that  affect  it. 
it  is  not  to  be  inferred  that  all  reversals  of  trop- 
isms are  adapted  to  meet  some  organic  need,  in 
many  cases  nature  ijoes  not  seem  to  have  conferreil 
upon  the  orgatiism  any  [lovver  of  reversal  \vh;itso- 
ever.  The  pomace-Hy  l)roso(>hila  is  positively  pho- 
totactic  in  very  strong  light,  but  Carpenter  has  shown 
that    when    an    intensity    of    4S0    candle    power    is 

9o 


'H 


Sliulirs  in  .htinidl  Bcha'i'wr 


ixatlicil  tin:  nin\LnK'n's  (it  the  insect  an;  nn  loiij^er 
Mctiiiitelv  i.iiiUi-(illLii.  The  tlus  tumble  aiui  uliiil 
abdtit  in  ail  iiTei^'ular  ua\,  hut  in  no  ease  elu  they 
shiiu    a   neyatue   reaetum. 

I  here  are  other  eases  in  uhieh  the  ixiwer  nt  re- 
\eisal  oeairs.  hut  \vh  re  it  is  not  hrouu;ht  into  phiy 
when  it  wnulil  secin  to  I'e  most  iieeileil.  I  he  hirj^c 
terrestrial  amphipoil  oi-  s.nul  t'ea  I  tih>r,  hi>tiu  iiiuji- 
i<n)ii>  is  onlinai-iU  llo^i'.i\^  in  its  reactions  to  li;^ht. 
\\  hen  tirst  exposeil.  esiKeially  it  it  is  uet  or  eoKl, 
it  ma\  sliow  a  saeillatinLJ  teiuleiiev  touaril  the  iie^a- 
ti\e  reaetion.  hut  in  strong  li^''^'  I'speeially  in  a 
hi^iier  temperature,  it  heeomes  strongly  positi\e.  I 
have  exposeil  specimens  m  a  dish  one  eiul  ot  which 
was  sJKuleil,  while  the  other  was  illuminated  In 
direct  sunlight.  In  the  strong  light  they  hecame  more 
strongK  |>ositi\e  aiul  persistcil  in  attem[)tiiig  to 
lump  toward  the  light  until  the\  were  o\ereome 
In  the  heat  aiul  died  in  a  heap  at  the  cnA  ot  the 
dish  toward  the  sun.  l>oth  tlie  intense  light  and 
the  heat  hail  the  eltea  ot"  rendering  the  positive 
reactions  ot    the  creatures  more  decided. 

Similar  heha\ior  is  shown  In  the  water  scor- 
pion Ranatra  when  it  [lersists  m  going  toward  a 
poweilul  electric  light  until  overcome  In  the  he;it. 
SuJi  hchavior  is  certainK  the  reverse  ot  adaptive. 
Nature  has  not  e(|uippcd  tlu-  I  alorchestias  ami  the 
Uan, It  IMS  with  am  metln)d  ot  propeidv  meeting  a 
situation  pi-esented  In  i  eoinhination  ot  strong  light 
and  a   latal  degree  ot   heat.     Such  combinations  arc 


The  Reversal  of   Trnpisw.s 


95 


nor  common  in  the  natural  cnv  Ironnunt  of  either  of  '■ 
tlicsr  spccifs.      lioth  ot   them,  in  common  with  mo>t 
other  animals,   hi^h   as  well   as   low.    resporui   nei,M- 
ti\el\-  in  ordinary  circumst.ii-.ces  to  an   iniui-ioi;s  Je- 
.U^rce  of  temperature.     Mrin<>;  a  hot  neeJle  near  either 
ot  them  arul  it  will  turn  awav.     But  the  remarkably 
strong  |)rocli\ity  of  these   forms  to   jj;o  touaril   the 
lij,'ht  is  suflicicnt  to  draw   them  into  a  rcfiion  which  ' 
they    would    ordinariK    shun.       If    thev    turn    awa\' 
at  times  trom  the  more  intens,;  heat  their  ph.itotaxis 
quickly   brin^rs   them   hack   airain.       Thev   he!ia\e    as, 
if  they  were  utuler  a  powerful  spell  which  thev  are  ! 
unahle    to    resist    and    which    they    ohev    as    lon^'    as 
any  ot  their  \ital  eiier^rv  remains. 

\\  hilc  there  are  many  animals  w  hich  cannot  he 
nuule  nefratively  phototactic  hy  any  increase  of  li^rhr, 
it  is  not  uncommon  to  \\m\  forms  that  are  positi\e 
in  li^dit  ot  weak  or  moderate  intensitv  and  nega- 
tive in  stronj^r  light.  \'ci-y  intense  light  is  often  ac- 
companied !iy  an  injurious  degree  of  heat  and  even 
where  it  is  not,  its  etteits  on  the  organism  are  proh- 
ahly  not  gootl  and  are  sometimes  manifestly  injuri- 
ous. I  he  power  ot  change  from  {Positive  to  nega- 
tive photofaxis  in  str(tng  light  is  a  serviceable  en- 
dowment with  whicli  we  might  expect  a  pi'mri  to  find 
many  organisms  ctjuippcel.  Curiouslv  enough,  it  is 
not  among  the  more  highly  orgam/etl  phototactic 
animals  that  this  ability  is  most  widespread.  In  (he 
insects  rcvei-sal  ot  the  positive  reaction  is  r.ither  un- 
common.     In  the  crusrace;ins  reversal  in  strong  light 


'/> 


Stndirs  in  .tnlmal  Behavior 


is  rather  more  often  fouiul  in  the  more  primitive 
members  of  the  j^roup  and  in  larv.r.  Reversal  m 
strong;  li^ht  among  the  h)\ver  invertebrates  is  fairly 
common  ami  especially  so  in  the  phytotlagellates  and 
other  forms  which  contain  chlorophyll  or  some  allied 
photosensitive  substance.  I'he  same  trait,  as  Stras- 
burger  and  others  have  shown,  is  frecjuently  mani- 
fested by  the  swarm  spores  of  alga-.  In  forms  con- 
taining chlorophyll,  light  is  intimately  concerned  with 
the  general  metabolism,  and  therefore  has  an  un- 
usually important  influence  upon  organic  weltare. 
Adaptive  behavior  in  relation  to  changes  in  light  in- 
tensity is,  in  these  primitive  forms,  almost  an  es- 
sential coniiitlon  of  existence. 

An  excellent  illustration  of  such  adaptive  behavior 
is  shown  by  the  movements  of  the  chloroplasts  in 
the  cells  of  many  plants.  It  is  well  known  that 
most  green  plants  bend  toward  the  light  so  that  a 
great  part  of  their  surface  may  be  exposed  to  the 
rays.  Often  the  leaves  move  under  the  stimulus 
of  light  so  that  the  rays  impinge  upon  them  at  right 
angles  (transverse  hellotroplsm  ) .  But  in  addition 
to  these  de\ices  for  securing  a  more  effective  ex- 
posure, another  adaptl\  e  feature  is  afforded  by  the 
moxements  of  the  indhi^lual  chloroplasts  within  the 
cells.  Ihese  chloroplasts  are  masses  of  protoplasm 
containing  chlorophyll,  in  weak  light  the  chloro- 
plasts are  arrangetl  along  those  sides  of  the  cell  at 
right  angles  to  the  rays.  When  the  light  is  intense, 
these  bodies  move  to  the  sliles  of  the  cell  parallel 


///(•  Reversal  of    Trnpi^ttis 


97 


will)    the    rays   where    they    eseape    exposure    to   the 
strotijfcr  stirmiius. 

A  \ery  strikin^^  e\hi!iiti<in  ot'  simihir  lHh:i\i(>r 
IS  shown  by  the  chI')rophists  of  the  lilamentoiis  al^a 
Mesocarpiis.  Aecordiiin;  to  Straslnir^er,  "the  ehh)ro- 
phists  in  the  form  of  a  sin^Me  phite  suspeiuied  in 
each  eell  turn  upon  their  lon^ntudinal  axes  acconl- 
injr  to  the  Jireetion  ami  intensity  of  the  h^ht.  In 
hirht  of  moderate  intensity,  accordinjj;  to  Stahl's  oh- 
ser\ations,  they  {)hiee  theniseKes  transverselv  to  the 
source  of  hjrht,  so  that  they  are  fully  illuminated 
(transverse  position)  ;  when,  on  the  other  hand,  they 
:irc  exposed  to  direct  sunli^dit,  the  chloroplast  plates 
are  so  turneti  that  their  edges  arc  directed  toward 
the  source  of  light  (profile  position)."  Analogous 
protection  against  too  strong  light  occurs  in  some 
diatoms  in  which  the  chloroplasts  when  intensely 
stimulated  become  aggregated  in  dense  clusters. 

Most  of  the  free  swimming  spores  of  algx'  and 
a  great  many  of  the  chlorophyll  bearing  flagellates 
keep  in  situatio.is  of  optimal  light  intensity  owing 
to  the  fact  that  they  are  positively  phototactic  in 
weak  light  and  negatively  so  in  strong  light.  The 
particular  intensity  of  light  in  which  any  form  tends 
to  rem.ain  depends  not  only  upon  the  species,  but 
also  upon  \  arious  conditions  affecting  the  individual 
organism.  'J"hat  the  organism  tends  to  remain  in 
a  region  of  the  most  advantageous  degree  of  illumi- 
nation cannot  of  course  be  asserted,  especially  in  view 
of  the  many   unadaptive   features   shown  by   tropic 


'»S 


Siihhi'^    ill    .hiiniiil    liiliJii"t 


Ih-Ii.i\  iiM'  ill  ;iuui.il,  I'lii  It  1^  \vy\  pinlMMf  that  tlic 
n^Miiii  Si,  Ki  till  ri.'picM.iiN  ,it  li.ist  ,1  rmr^li  .ipprnvi- 
ni.itiiiii   to  till'  ii|itiniiiin. 

Intim.iti'K     M'latiil    to    llir    ittii.i    dl     iiiitiisit\     nl 

IlL;ill     I.:;     Iillu'nt.l  \|s     !•,    tllC     mllllClCC    n|     |M\\|iius     ca- 

pii'-ui"!.-.  (irnnin  aiul  I.ik!i  m  tluir  >il>s(.  |-\  afmiis  on 
I'alami.  !ar\a'  Imi.'ui  t!iat  ilust-  "r^atiiMiis  u  i.  I'c  jiii>i- 
livc  i:i  tlic  iiinrniii;,',  i\i.ii  In  iiuiti.-  stMHi^  li^ht.  and 
that  latif  in  the  J  i\  tlK\  hi.iainf  iic^afivc,  even 
llimijrh  tho  hy;ht  to  uhiih  tlu\  U(  tc  lApostnl  became 
ieihK(.il  in  iiitiMsit\.  I  !iat  this  is  not  the  result 
(>(  a  iliiinial  i-|i\t!;m  is  shuwii  hv  the  Lut  that  pusi- 
ti\e  lar\a'  phue.l  Id-  a  tew  Imhiis  at  am  time  of 
Ja\  m  a  (iai^k  eiulosure  will  he  positue  ulieii  first 
expdseil  td  nt;lit.  Simihir  iieliavior  is  sliowii  hy 
Daplniiu  i>iih/ihi,  exeipt  that  in  moiierate  hijht  the 
a.nimals  heeume  nuliHerent  aiul  shuu  a  negative  re- 
aetidn  when  the  iiitensitv  of  tfie  liuht  is  itiireaseti. 
After  exposure  to  a  stronger  Wiiht  tlie  Daphnias 
ai^ain  heeome  iiuhtterent  atiii  reijuire  a  still  stron^^er 
hi^ht  to  produce  a  ncLjatiw  response. 

I  lie  ehise  connection  hetween  the  inlhienee  of'  in- 
tensity of  h^ht  and  time  ot  exposure  is  shown  h\ 
the  tact  tliat  forms  that  are  positive  in  moderate 
n^rht  treijuently  do  not  immeiiiately  become  nega- 
tive when  stroni^r  h^ht  is  throw  i  upon  them.  Stras- 
burL,^'r  found  that  the  swarm  s[iores  of'  I  hithrix 
which  are  positive  in  weak  li^ht  remained  positive 
tor  a  V  erv  short  time  when  exjiosed  to  stron^,^  h^dit. 
liahinus   larvii;   rendered  positive   by   being  kept   in 


Till'  Rrzi'r<til  (if    Ticpi-tus 


•>•> 


J.irkiu'ss  swim  toward  strdiiLJ  li^lit  lor  .i  slmrt  tiiiii' 
lulnrc  tlu\  sIkiw  till.'  iu')^ati\c  rt-.u timi.  I  lu' 
^tr(iiim.r  tlir  li^ht  the  i]uli.k(.r  the  lui^ativc  n  avtimi 

In  aiKlitmn  to  thrsc  ciian^i's  in  rL-aition  w  c  liavr 
till-  slower  ailuistiiKiu  ot  Mianv  organisms  to  the 
(.ontiiiiKil  inllin-nci.'  of  a  particular  inti.tisit\  ot  Ii;j';i 
\(ia|itatioiis  of  or^,Miiisms  to  stiniuli  to  wliiili  tli  v 
ire  lialiitualK  ixposeii  are  eoiniiioii,  aiui  tlie  lases 
ot  so-ealUnl  ii),r|it  attiiiienieiit  ina\  he  re^arileil  as 
I'artieular  iiistaiiees  ot'  this  general  proee-s.  Mie 
ijiatoiii  \  (/:/.///(/  Iniii\  is  positi\e  oiiK  in  tiie  weak- 
est Ht^ht.  \  erwiini  exposed  a  eiiltiire  ot  this  spe- 
cies to  a  wiiuiou  tor  two  weeks,  alter  whicli  the  ilia- 
toins  heianie  positi\  e  in  hLi;ht  to  whiJi  at  lirst  thev 
^a\e  the  nei;ati\e  reaetioii.  Xeeonlin^  to  Stras- 
hiir^ur  the  swarm  spores  ol'  al;^a\  il'  kept  exposed 
tor  a  eonsiderahle  time  to  ielati\cls  strong'  I'u'^^ 
will  reaet  [positively  to  a  mueh  stronger  intensity  of 
lij^'ht  than  they  did  previously.  Similar  phenomena 
have  heen  noted  hy  (  )ltmanns  and  In  Mast  in  \'ol- 
vox.  Ordiiiarilv  the  exposure  ot'  \'olvox  to  stront,' 
lii^dit,  it  not  jM-olon^ed,  has  the  cHeet  of  makifi^  the 
ori,Miiism  iiej^ative  to  li<,dit  in  whieh  it  had  previously 
heen  positive.  I  jowever.  a  longer  exposure  to  stronjr 
liii;!it  will  have  the  reverse  eftect  of  raisini,^  the  opti- 
mum, the  ori^anisms  i-etainiiiL;  the  positive  reaetion 
il.  liiiht  whieh  wouKi  otherwise  have  produced  a 
net,Mtiv  e  response. 

I  rom  the    tore^oini^   taets   we  may  coneludc  that 


I<  )f ) 


SiiiJiis    til    .tn'niidl    fiflhiiinr 


i.'\[)()'.utc   tc   li^,'Iit   nia\    attiHt   or^i.misins   in   two   <lit'- 
KriMt    ways.      Cdtitituird    stiimilation    iiia\     rciiilcr 
positively   phototactic   (ti-;;anisnis   iic^ati\r.      It   tnav 
also    hrin^    about    a    chancre    of    Iij,r|it    attuiicmcnt. 
thcTfhy   iliillin^r   the   sensitivity   of   the   or^Miiisin    so 
that  if  re(|iiircs  a  strony^cr  stimuhis  to  evoke  a  nega- 
tive   reaetion.       I  hese    two    opposed    results    are    In 
MO    rjieans    exeeptioiial    phenomena :    they    are    (|uite 
parallel  to  many  other  physiolo^rical  ehan^es   whieh 
remier  the  ortj;anism  less  sensitive  to  habitual   stim- 
uli.      I  he  one  is  a  ehan^e  wr<tuj.;ht  in  the  orj^anism 
as    a    direct   result   of   the    stimulus,      'i'he    other    is 
a    response    hy    the    organism,    a    sort    of    defensive 
measure,  by  which  the  or^i;anism   becomes  more  or 
less  shieKled   from  the  action  of  an   inimical   force. 
Accorilin^  to  the  relative  potency  of  these  two  moili- 
fyinjr    factors    the    effects    of    previous    exposure    to 
li^ht  will   naturally  be    varied.      .ShouKI    attunement 
to  increased  inte":.:ty  of  lif^rht  l)e  (juickly  developeil, 
the    effect    of    continued    exposure    itii^ht    a[)pear   to 
make  tiie  positive  reaction  more  decided.     The  ef- 
fects uf  exposure  to  liijjht  arc  notoriously  different  in 
different  forms,  but  many  of  these  variations  may  he 
the  result  of  the  varying  potency  of  the  two  influ- 
ences we  have  discussed. 

I'xposure  in  certain  cases,  however,  affects  rc^ 
versal  in  ways  for  which  it  is  difficult  to  account. 
When  stuilying  the  light  reactions  of  terrestrial  am- 
phip(»ds  I  discovered  that  specimens  of  OrchcsiUi 
(Ujiiis  which  were  markedly  positive  quickly  became 


Thr   Rrvrrud  of    Trnpisms 


lOI 


iu^ati\i.  iipnn  iliriiimitioii  nt  t!u-  Ii;;lit.  Orilinarily 
w  111  n  tlu'sc  forms  arc  phucii  in  i  ilisli  aiul  cxpitstnl 
t'l  a  wiiuldw  tluv  kcip  running  ami  Imppini^  in  the 
.iinctioii  of  the  li^ht.  1 1  now  the  dish  is  larricil 
!>  Ilk  into  a  Jark'.T  part  of  the  room  the  whole  troop 
of  ()rihestias  will  tiiiii  about  aiiil  lloek  to  the  nej^a- 
ti\e  end  of  the  dish.  Alter  hein;^  kept  lor  a  half 
hour  in  the  darker  part  ot  the  room  the  amphipods 
a^ain  become  positive,  it  they  .ire  now  carried  to 
a  [lart  of  the  room  in  which  the  li^ht  is  still  less 
intense  the  negative  response  appears  once  more.  It 
the  Orchestias  are  I^rou^ht  I'ack  into  more  intense 
li^ht  they  almost  immediately  become  positive  aj^ain; 
and  the  positi\c  reaction  appears  the  more  ijuicklv 
the  strony;er  the  li^ht.  Usually  the  transition  from 
weak  to  stronp;  li^ht  causes  positive  forms  to  be- 
come nejjative.  In  the  (Vchestlas  we  find  just  the 
re\erse.  The  transition  from  positive  to  negative 
or  the  reverse  occurs  so  quickly  that  it  is  scarcely 
possil^le  that  chanjje  in  lij.;ht  attunement  plavs  a  part 
in   the   transformation. 

Hnc  might  expect,  ti  prinri,  to  lind  tropisms  occa- 
sionally re\  ersed  liy  temperature,  so  profoundly  does 
this  factor  influence  all  forms  of  behavior,  especially 
in  the  lower  organisms.  Strasburger  found  that  the 
swarm  spores  of  many  alga-  are  positive  at  higher 
temperatures  and  negative  at  lower  ones.  Massart 
finds  that  the  Magellate  Chromulitia  is  ;  ■';sitive  at  2n'' 
C,  but  negative  at  5  C.  .\ccording  to  I.ocb  the 
larva.'   of  Polygordius  which  were  negative  at    16^ 


i'>l 


Si/iiln'^    ill   ./iiiiiiiil   /{,li,iiii)r 


C.   hre.iinc   [Kisirivr   when    (.ndkd   tn   (>      C.      I'\cc[i- 
'i""^il    iiiili\  l.liials    whiJi    \wi\'    positlxf    at     17      to 
^-1     luiaiiic  iniratlv'.'  at  a  tempLTaUire  of  2<)   .      M.i- 
lini   i()).i'|)ii(N  were  Iniiihl  In   I  oeh  to  !h-  attettfil  in 
a    smtilar    ua\.       \cLiatl\v-    spci.  :nKtis    of    Onhr.^iui 
>h///i^    I    liave    loiiiiil    t(i    !,,•    naukrcil    ]tositi\r    rnin.li 
more  (juiikK  il  tlu  teinpi.  ratiiri'  is  raiscJ.      Tho  same 
is  rriie  tor  tl.e  water  seorp.ioii  l-Iatiatra.     <  )n  the  otlier 
liaiiil.   Dr.   Dice  o!i-,er\ei|  that  in  /).//>//;//,/  /•///•■  v  h)\v 
temperature  exdkes  the   positive   res[>onse.      .\(ul   ae- 
eordi!!-^    to    I'uahl    increase    of    tem(ierature    makes 
posiiive   hir\a'    of    Mahimis    negative    while    ileerease 
ot  tempei-atiire  makes  iienr,iti\  e  hir\  .r  po-itiv  e.     Da\- 
eiipiwr    alter   liiscussm^   the    etteets    of   temper. .are 
on   phototaxis  states  that   "All    results  may  he   har- 
inoni/ed  in  the  expression:      Diminution  of  teiTipera- 
ture  below   the  normal  laiises  iw  ersal  of  the  11    ■•nal 
response;  elevation  of  temperature  to  near  the  maxi- 
mum accelerates  the  normal  response."     I'xceptions 
to  this  formula   are  aflorJeJ  In    manv  of  the  larvii- 
ot   i'ol\;.r,,rJli|s  ami  In  certain  species  of  amphipoils, 
hoth  ot  whiJi  are  changed  from  positive  to  nej.fati\c 
at    an    unusua.lly    hiu;h    temperature.       .Many    forms 
which   are  chan^^il  from  jiositive  to  negative  by  ex- 
I'osure  to  lii^rht  are  chaiifrcil  nKu-e  .juicklv  at  a  higher 
temperature,  but  the  swarm   spores  of  alga-  appar- 
cnrlv    form    an    exception    to    this    rule.       Iherc    are 
u'ativ    organisms   in    which    the   sense  of   the   photo- 
tactic  reaction  remains  the  same  at  all  intensities  of 
light,  and  in  these  cases  temperature  usually  has  no 


Till     Riirruil   "f    /'rdpi^my 


I"*;? 


;'u\\i.r  to  rc\crsc  tin."  rcsii(iii>,c. 

<  >rlu  r  troiiisnis  :u\'  nnt  so  t  rn|u(iitl\  ii.\  (.rscil  liy 
ii-iiiiKTaturc  cliaiiL!;cs,  l':irki.r  rouiul.  liow  ex  it.  that 
ill  tlu-  (.(ipipoil  I  .ahiiloura  t\\c  tciiialcs  u  i  re  posi- 
ti\i.I\-  pliototaetK"  i'l  warm  uatiT  atii]  ini^ativc  in 
lolil,    the    rntual    teinperature    In'm^    about    zU      C. 

I  he  motaxis  ol  the  maK>,  like  their  p!iotota\is,  is 
weak.  Dr.  I)iee  ob^erveJ  that  f):i/>liii!<i  piilix  t-  ii>|s 
to    W    positi\el\    phototaetie    at    hi^h    teiii|K'ratures 

nul  iiei^ati\  e  at  low  oiu  s.  Se\  era!  proto/oaiis  w  hich 
are  iie^nitiv  el\  ^eotaitie  at  orJinarv  temperatures 
heeome  po^itixe  a  tew  decrees  aho\  c  o  C,  hut  it 
Miav  he  tliat  in  some  ot  tiiese  eases  low  temperature 
proiiuees  a  eonJition  ot  inaeti\itv  that  lea^ls  the  or- 
L^anisms  to  settle  at  tlie  lower  end  of  their  etulosurc. 
It  is  a  eurious  t.ut  that  the  sense  ot  an  animal's 
response'  to  li.^ht  may  he  iletermined  h\  the  stimuhis 
ot  eoiitaet  with  some  solid  object.  Contact  stimuli 
projoundly  aHeet  tlie  irritahihtv  ot  main  or;^a?iisms 
.•.n^\  eo;ise(|uently  ha\e  a  marked  intUienee  on  their 
heha\  ior.  I  he  instinct  ot  feii.jninij;  death  which  is 
usually  elieitcil  as  a  response  to  contact  and  which 
we  !ia\e  elsewhere  suu;u;estetl  is  an  out)j;rowth  trotn 
thijrmotaxis,  is  usuallv  accompanied  h\'  a  tetanic  eon- 
tiaetion  ot  the  niuseles  and  a  reduced  setisiti\  eness 
to  stimulation.  It  is  probahlv  on  account  ol'  the 
marked  iniluence  ot  contact  upon  the  phvsiolo;^ical 
states  ot  the  lower  animals  that  we  sometimes  tinil 
contact  stinuili  causinu:  ^i  rexersal  ot'  the  resj)onse 
to   light,      Hue   ot"   the    first    cases  of   this   kind    was 


I04 


Siiidit's  in  .luinuil  Bchaiior 


foiitul  hy  Miss  I'owlc  in  the  ostracod  cru'^racLari 
Cypridopsis.  Ordinarily  iicj^ativc,  this  inr.Mi  could 
he  rendered  posiri\e  hy  heinf,^  pickeil  up  by  a  pipette 
and  drojipeil  out  aj:;ain.  Often  specimens  were 
chanjrcd  from  negative  to  positive  when  they  col- 
Hiled  with  the  side  of  the  dish.  In  an  alhed  form, 
Cypris,  Yerkes  observed  similar  changes.  Parker, 
on  the  other  hand,  found  that  in  the  copepoii  I.abi- 
docera  positive  specimens  could  be  rerulercd  net^a- 
ti\e  by  handling  them  with   a   pifiette. 

I  he  influence  of  contact  on  the  pliotota\i>  of  l\an- 
atra  is  very  marked.  I  landlini;:  this  itisect  throws 
it  into  a  death  feint  which  itihibits  at  first  all  photo- 
tactic  response,  but  soon  after  tlie  creature  begins 
to  rouse  itself  and  slowK  walk  about,  it  fre(]uenriy 
manifests  a  tendenc)  to  slink  awav  from  the  lij^ht. 
On  further  exposure  this  tendency  is  superseded  bv 
the  positive  response  wliich  becomes  more  ilecided 
until  the  creature  is  wrought  up  to  a  pitch  of  frantic 
excitement.  Reversal  by  contact  is  verv  clearly 
shown  by  this  insect  if  when  it  is  swimmin;.;  toward 
the  lijrht  it  is  seized  and  gently  stroketi,  or  simply 
pickeil  up  by  the  tip  of  the  brcathin<,r  tube  and 
dropiK'tl  back  aj^'ain  into  the  water.  Curiouslv  enough 
Ranatra  tloes  not  fei^ni  death  while  in  the  water,  or 
at  least  it  iloes  not  .t,nve  more  than  a  momentary 
sujr^estion  of  such  w  performance,  but  the  stimuli 
which  would  at  once  cause  it  to  feiyn  death  when  in 
the  air,  priKhkc  an  immetliate  reversal  of  its  phot(>- 
taxis  while  in  the  water. 


Tlw  Rcvrrsiil  of    T topis ms 


lo; 


It  is  prulnihlv  owin^  to  the  inlUicncc  of  contact 
that  positively  phototactic  sficcinicns  of  Orihcstia 
iUjilis  become  immediately  aiul  strongly  nejj^ative 
wlien  tiiev  are  thrown  into  the  water.  I  ha\e  shown 
;liat  this  interesting  reversal  is  not  the  result  of  tem- 
perature chani^es  or  chanj^es  in  lit^ht  intensity.  It 
occurs  in  the  same  way  whether  the  water  is  warmer 
or  collier  than  the  air  or  at  the  same  temperature, 
ami  whether  there  is  an  accompanying  increase  or 
decrease  ot  illumination. 

Reversals  of  tropisms  hrouj^ht  about  by  chemicals 
are  common.  Aiklition  to  the  salt  content  of  sea 
water  was  found  by  Loeb  to  make  nejj;ative  speci- 
mens i)i  I'ohirordius  larva'  and  certain  copepoiis 
positive.  I'ositive  specimens  of  the  same  forms 
vv  ere  made  nct^ativ  e  by  diluting  the  sea  water.  I.oeb 
rendered  the  normally  negative  Gammarus  positive 
liy  the  addition  of  carbon  dioxitle  and  other  acids. 
Cyclops  and  Daphnia  were  rendereil  positixe  in  the 
same  way.  Positive  specimens  of  Diaptomus  were 
fov.nd  by  Moore  to  be  made  negative  by  strychnine, 
but  this  negative  reaction  may  be  reversed  by  aciiis, 
caffeine,  and  other  substances  which  ordinarily  tend 
to  produce  or  emphasize  the  posit'ive  response. 
I". wart  tliscov  eretl  that  Halanus  larvic  were  rendereil 
positive  by  acids,  certain  salts,  and  by  hypertonic 
sea  water,  while  alkalies  anil  hypotonic  sea  water 
made  them  negative.  Sev  eral  of  my  students,  Jack- 
son, Michencr  and  Dice  who  have  investigated  the 
problem   have    shown   that   there   is   little   apparent 


lor, 


.S///i//('*    ///     lii'niiiil    fiilhiiinf 


i\!;iliiui  liiturm  the  tl:is.  n\  iluiiiit.il  unci!  aiul  the 
iiilliHiUi-  111  the'  sul>.tani.r  mi  ; 'hnti  itaxis.  The  cxpci-i- 
inciifv  nt  latksMii  Ml!  the  iVesh  u  at  r  ainjihipml  I  Ival- 
Iflla.  uhiili  Is  iiiiriiialK  n>Lrati\i.\  \\.i\j  sliown  that 
piisiti\c  phutiitaxis  !iia\  he  pr^uhieeil  h\-  sc\cral  aciJs, 
ani;iii-i)iuiii  h\(hM\M  ,  and  'r\ri-al  nther  ehciiiiials. 
MiJiemi-  liiiii'.''  m  eNjii  niiu  I'tin^  with  a  iminher  nt" 
(hwrst-  lonn-.  ihat  it  tlie  i'e^|.iin^c  is  in-L,Mti\c  it 
!na\  he  reiuK  I'eil  |i((siii\f  \.\  jKiimaK,  ahhou^h 
[iMsitix  e  toian^  are  rai\-|\  tna.le  tieij;ati\e.  Aeiils. 
alkalies,  sahs  aiul  \ari<iiis  dthir  ehemiials  i>\  tlie 
most  ihNei-ve  sm-ts  wouKl  Mlt>-ii  JiaiiLje  the  jihntu- 
ta\is  t  rniji  iir^ativ  e  tn  pl)^iti\  ,-.  '(Iktc  was  a  marked 
similarit\  dt  itteel  jiriuhkeil  h\  ehi-mieals  ot  the  must 
ih\  iTse  kinds. 

\\  hile  reaction*-  ti.  hi^lit  ma\  he  re\ersrd  h\  manv 
agencies.  li:,rlit  in  turn  ma\  reverse  reactions  to  otiier 
stimiih.  During  the  hist  tew  \ears  there  have  a[i- 
peared  several  interestinL^:  studies  on  tile  intliienee 
ot  Hifht  and  other  a.^eiuies  on  res|)onses  to  ^raxitv. 
Isterlw  in  stud\inj,r  the  reaetions  ot'  the  copepod 
C  alamis,  found  that  indi\  iduals  when  in  the  liark  he- 
came  neLiali\el\  L,a'otaetie.  Init  when  ilhnninated 
elthei-  li-on)  ah.o\e  i^v  iVom  hilow  the\  swam  liown- 
uard.  Snnihir  heha\ior  was  ohsi'rvid  h\  Harper 
ill  the  hir\a  ot  'he  ll\  Cdreihra,  hv  l'>auer  in  the 
erustaeean  Maeromysis,  and  hy  .Me(iinnis  in  the 
tairy  shrimp  iinnuhlpus.  Tile  recent  work  of  Dr. 
Dice  on  ilir  vertical  mit,r|-ations  ot'  I)a[)linia  lias 
shown  that  tlie  ehaiii,rcs  in  the  vertical  miiirations  of 


77/('   R,  I,  )  uti   nf    T)  <,p: 


lit  y 


I"' 


ilk'si.'   tonus  aiT  iidt  SI)  iiniJi  the  Jimt  ifiLct   nl'  yc- 
:iili(ifis    to   h^lit   ;;•>   tlu'    i\suli    ot'   llu    \\,i\    in    uliali 


lit    alter 


I'vSl'OilM'S      III 


:i-.i\  ,;\ . 


)a[>iiii,.i->   swim 


iipwarJ  in  t!ic  dark.  luit  wlicii  illuniinateii  tl)f\  swim 
\  i.^oronsly  ilouiiu  ai\l  i-cL^arillc^s  oi\linaril\  ot'  the 
Jiieetion  in  uhiih  hijiit  tails  upon  them. 

In  many  Khi/opoJs  the  tln;,Mnotaetie  respoiise  is 
I'osit;  to  weak  eontaet  stimuli  aiul  ne^Mti\e  to 
stroii;^  ones.  Similar  relations  are  touiul  in  |)la- 
narians.  Striking  cases  ot'  the  re\ersal  ot'  electro- 
taxis  lia\e  been  tijscriheii  in  a  numhcr  ol'  iii\erse 
t\[>es.  \  o|\()\,  whiJi  normally  swims  toward  the  ca- 
tlioile,  may  !k-  caused  to  swim  to  the  anode  hy  kccp- 
iriLi  it  tor  tw(i  or  three  da\s  in  the  dark.  Keexpo- 
sure  to  light  soon  brings  about  the  normal  response 
(Icrry).  Similar  le-.ersals  ot'  elearotaxis  ha\c 
been  observed  by  Moore  and  doodspeeJ  ti)  be  pro- 
duced iti  (ionium  by  either  acids  or  alkalies.  And 
Bancrot't  (  i  )  has  shown  that  i'aramnvlum,  which 
usually  swims  to  the  cathode,  may  be  caused  to  swiin 
to  the  anode  by  \arious  salts  ot  soiiiu.ii  AnA  potassi- 
um. Certain  salts  were  lound  to  cause  l'aranM\ium 
to  swini  backwards  to  the  anode,  a  rc:iLtion  dittering 
Irom  true  [lositixe  or  a.nod.il  eketrotaxis  in  th.it  the 
organisms  swim  backwaril  instead  ot'  t'orwaril. 

I  he  reatler  who  has  had  tlie  patience  to  t'olb.w 
the  discussion  thus  tai"  wdl  a[){)reciate  not  only  how 
wide  spreail  is  the  reversal  ot  tropic  reaction,  but 
how  x.incd  are  the  i.auses  b\  whith  reversal  mav 
be  produced.      .Moreover  It  is  ditiicult  to  make  any 


ic)8 


.S///(//(>   ill  .  I  III  III  til  ficluivior 


m.ncrali/atiiin>.  rc^ardin^  the  rcN  crsal  of  tnipisms 
licfausc  tlu-  ^amc  (actors  ot'tcn  cause  i|uitc  opposite 
cftccts  ill  ilitkrciit  or;^aiiisms.  Iiurcasc  ot  tcm[icra- 
turi.',  as  \\c  ha\c  seen,  may  Jiiii^c  ptiototaxis  from 
positi\c  to  iu-;^ati\c  in  some  tonus  aiul  from  iie^a- 
ti\e  to  pos!ti\c  In  otfiers.  Contact  stimuli  act  in 
the  same  \\a\  as  shown  by  their  i.lilterent  inlluence 
on  the  li^^ht  reactions  i>\  C'ypriilopsis  aiul  Daphnia 
or  Ranatra.  I'.xposure  to  darkness  temls  to  make 
some  species  positive  and  others  negative,  and  ex- 
posure to  stronfj;  IiK^it  produces  simihir  \aricil  re- 
sults. These  ap[iarently  eontrailictory  torms  of  be- 
havior will  probably  be  reconciled  when  we  ha\e 
ac(]uired  a  lieeper  insight  Into  the  physlolofrical 
mechanisms  inxohed  in  tropic  reactions.  1  hus  tar 
we  have  had  few  serious  attempts  to  explain  the 
phenomena  of  re\ersal,  owinj;  probably  to  the  difH- 
culties  and  perplexities  of  the  undertaking^. 

!)r.  B.  Moore  in  the  course  of  a  pa})er  on  the 
light  reactions  of  certain  marine  organisms  has  de- 
velopetl  a  \iew  whicli  he  expresses  as  follows: 
"lioth  the  positive  and  the  negative  behavior  to 
light  may  lie  explained  on  the  basis  of  one  chemi- 
cal action  of  the  cell  (a  katabolic  one).  The  posi- 
ti\"e  state  indicates  that  the  speed  of  reactions  in 
the  ce"  lies  below  a  certain  value,  which  may  be 
called  the  optimal  value,  and  the  negative  state  cor- 
responds to  a  speed  of  reactions  in  the  cell  abo\e  the 
optimal  \alue.  In  the  former  case  the  sentient  sur- 
faces are  turned  Into  the  light  to  increase  velocity 


The  Reversal  of   Tropisms 


109 


of  reaction  up  towanis  the  optimal  \aliic;  in  the 
latter  case  the  sentient  surfaces  are  turnetl  away 
from  the  li^ht  so  as  to  decrease  the  velocity  of  rc- 
aitions  ilown  toward  the  optimal  \alue.  As  a  result 
(if  the  orientation  so  caused  there  arises  movement 
of  the  organism  towariis  or  away  from  the  source  of 
r^lit,  hut  such  orientation  is  not  a  fixed  orientation, 
luit  lather  a  steerini,'  action;  the  animals  as  a  result 
do  not  remain  in  one  lixed  plane  or  ilirection  ot 
movement,  hut  the  ixt  result  of  the  movement  is 
that  the  organisms  mo\  e  to  or  from  the  lif^ht." 

This  explanation  is  one  that  is  little  more  than  a 
statement  of  the  facts  to  he  explained,  it  is  highly 
prohahle  a  priori  that  the  specil  of  reactions  in  the 
stimulatnl  cell  would  increase  with  the  intensity  of 
the  stimulus,  and  to  say  that  when  these  reactions 
!iecome  sutticiently  rapid  the  sentient  surface  is  turned 
awav  tells  us  no  more  than  that  under  these  C(jn- 
ditions  the  organism  becomes  negatively  phototac- 
tic.  In  Moore's  piper  there  is  no  recognition  ot 
the  fact  that  some  organisms  are  negative  when  first 
exposed  and  teinl  to  become  positive  the  more  rapidly 
in  more  intense  liglit. 

Another  interpretation  of  the  reversal  ot  trop- 
isins  has  been  given  In  Mast  (  i  )  in  his  paper  on 
the  light  reactions  of  N'olvox.  I'he  endeavor  is  made 
to  correlate  the  reversal  ot  tropisms  with  the  rever- 
sibility of  chemical  rcictions.  It  is  well  known  that 
chemical  reactions  mav  proceetl  preilotJiinantly  in 
one   or   another  direction    acconiing  to  the   amount 


I  l<> 


Siiiility    ill   .liiiiiitil   Hiliiiii'ir 


ot  siilisiaiuc  in\<iK(.il  ami  \  arums  (.xtcrnal  Lutdrs, 
sikIi  as  tcinpL  raturc  ami  m  sdiiif  cases  li^lit.  lor 
iii-.taM(.c  it  aknhi-l  is  ail.kil  to  aictii.  acitl  one  will 
iiltain  i.tli\l  acitatf  aiiii  watii".  < 'ii  the  dther  liatul, 
water  aiKle-1  to  etli\l  acetate  i"e>ults  in  the  toi'ina- 
ti'iii  n|  aKuhol  ami  aietie  aeul.  i  he  reaetinn  in 
eilh^i"  (..ise  diH's  lint  j.ine.eil  until  all  nl  the  (in^iiiiai 
suhsiaiiees  are  t  raiisldniieil,  Init  miK  tn  the  point  at 
\\hiih  ei.rtain  |'id|ioi-tioiis  ol  aleoiiol.  aeetie  aeiil, 
ttii\i  a.e.ate  ami  ualer  arc  i\ailuil.  I  his  repre- 
scnis  the  uiiulitioii  ot  iheniital  eijuilihriuin.  I  he 
relaii\e  pro[>oi  i loiis  ot  tlie  eoinpoumis  present  when 
iluiiii^al  e(|Uii;i'riiii:i  is  riaJieil  ilepei'al  ui'on  \ari- 
oi:s  c\ie:;ial  tauors.  >o:iKiiiiiv  s  one  cheinual  ehan^c 
iii.!\  iKeur  in  the  huht.  while  the  re\ersi.  |)roeess 
takes  phue  in  the  ilark.  I  mier  the  iiilUieiiee  ot 
hj^ht   the   lollowm^  iwietioii  oeairs : 

iA.nCl  X-cl       CI, 

while  in  Jarkr.ess  theie  is  tiie  rexerse  change 

.\-,U  CI  2.\uel. 

Main  other  i.oin(iouiuls.  e-|ieeiall\  the  t  iil^orides, 
show  a  similar  re\eisal  uiuler  tlittertnt  intensities 
ot  li.L!;ht.  In  eertain  eases  ■Iieinieal  reactions  are  at- 
tectcil  in  speulic  wa\s  1>\  tlu'  liitterent  rass  ot  the 
s[>eariim. 

"  I  o  explain,"  sa\s  Mast,  "rexersal  in  the  sense  ot" 
re.utioii  on  the  basis  ol  Jieinical  re,ictions  induceJ 
l'\  liiiht  let  IIS  assume;  i  i  )  I  hat  XOKox  contains 
suhst.iiKcs  X  ,iml  ^  ,  the  chemical  reaction  between 
whiih  Is  rcLiulatctl  b\   tile  inteiisitv  ot   lij^ht:   (  l)   that 


I'lir    Riicruil    (if     I'l'ipi'^niy 


I  I  t 


a  sub-optinuiiii  intciisitv  taxors  thi'  ti)iin;Uii"i  d 
substances  rcfircsciircil  h\  \  ami  a  supra-optiimim 
rfutsc  rc[ircsL'Mtcd  by  \  ;  atul  '  })  tbat  tbi-  lolnnii.^ 
arc  neutral  in  reaction  ulicn  there  are  ^  substances 
in  one  niember  ot  tlie  e(|uation  aiul  \  in  tlie  other; 
positive  wfien  one  tneniber  contains  (  X  )  sub- 
stances anil  tile  otlier  (V  ),  an>i  negative  when 
one  contains  (\  )  and  the  otlier  (V  )."  \  oj- 
\()X  is  positi\e  in  weak  liji;ht  arui  ne^ati\e  iti  stion^, 
but  when  placeil  in  li^ht  ot  supra-optimal  intensity  it 
does  not  immediately  chaiij^e  its  response.  I  his.  as 
Mast  sujj^f^ests.  mav  be  due  to  the  fact  that  some 
time  is  reijuired  to  translorni  the  substaiue  \  upon 
wliich  the  positive  reaction  is  supposcil  to  depend. 
Alter  tiiore  ot  V  was  produced  and  the  amount  ot 
\  diminished  through  the  action  of  more  intense 
ll^ht  the  negative  reactions  would  be  initiated 

This  ititerpretation,  which  is  confessedly  \  erv  spec- 
ulative, not  improbably  contains  elements  of  truth. 
It  is  probable  that  rcNcrsilde  themical  leaaiorr^  et- 
tect  the  general  restoi  ,tion  of  organic  eijuilibrium 
which  hail  been  disturbed  bv  the  inlUicnce  ol  the 
stimulus.  Whetlijr  positive  and  negative  photo- 
taxis  depend  on  the  relative  proportions  of  the  sub- 
stances bclonj^in^  to  a  single  eiju.ition  is  ot  tourse 
very  [iroblematical.  It  mij^ht  be  that  the  formation 
of  a  substance  .\  which  is  favored  bv  inten^itv  ot 
li^ht  brinj:;s  about  a  ne;rative  reaction,  while  the  posi- 
tive reaction  miy;ht  depriid  upon  the  torm.ition  <jt 
another  substance   B  which   was  not  connected  with 


I  I  2 


.S'///J/<<   ill  .tiiiiiial  'HtluniDr 


A  at  all.  W'f  arc  warrantcJ  in  asMim'm^i;  that  the 
ability  to  rcspniul  to  li^ht  dcpcmis  upon  thr-  exist- 
ence of  substances  that  uinKr^o  photocheniical 
changes.  The  eHeet  of  lij^'ht  wouKl  lie  to  exhaust 
certain  substances  anil  to  cause  the  accumulation  of 
their  protlucts.  I  hese  products  when  they  exist  in 
a  certain  iie^;ree  of  concentration  may  stimulate  di- 
rectly or  iiulirectly  (possibly  through  their  influence 
on  oxyJative  processes)  certain  locomotor  mechan- 
isms, wliile  at  a  lower  ile^'rce  of  concentration  other 
mechanisms  mav  be  more  stimulated.  It  may  not 
be  necessary  to  make  aiu  ()articular  assumptions 
concerninj^  the  role  ot  reversible  chemical  reactions, 
althou^fh  the  fact  that  such  reversibility  is  a  ^r^neral 
[M-opertv  of  chemical  changes  is  naturally  involved 
in  any  explanation  ot  recovery  trom  the  ehects  ot 
stimulation,  and  indeed  in  the  inter[iretation  ot  many 
(,ther  \  ital  phenomena. 

To  give  a  concrete  illustration  ot  how  reversal 
may  occur  accordinij  to  the  precedinLj  interpretation 
let  us  consider  the  reactions  of  IManaria  to  weak 
and  strong  mechanical  stimuli.  It  has  been  shown 
by  I'earl  that  Planiiria  iiuiiiilata  reacts  positively  to 
very  weak  mechanical  stimuli,  and  in  tact  to  very 
weak  stimuli  of  many  kinds,  while  to  strong  stim- 
uli it  gives  the  negativ  e  reaction.  I  he  positive  re- 
sponse is  brought  about  by  the  contraction  of  the 
longitudinal  muscles  near  the  stimulated  point,  in 
the  negative  response  the  planarian  turns  away,  not 
like  a  higher  animal  by  the  contraction  ot  the  muscles 


Till-  Rricrsal  of   Tropismi 


"3 


ut  the  opposite  s'nic  ol'  the  hotly,  hut  hy  an  .utiial 
h  n^thcnin^i:  ot'  the  stMiuilated  siile.  This  leiifjthcn- 
itij^r  is  prohahly  eHecteii  hy  the  eontraction  of  the 
>|(irso  \entral  inuseles  which  run  from  the  dorsal  to 
the  ventral  hody  wall,  aiul  possihly  also  hy  the  cir- 
uilar  tniiseles.  Ihe  response  is  local  and  ne.  r  the 
^timulated  area  as  it  generally  is  in  the  lower  inver- 
tebrates. The  positi\e  and  the  nej^ative  reactions 
de[>eiul  either  upon  the  functioning^  of  two  quite  dis- 
tinct reflex  arcs.  or.  in  case  the  afferent  impulses 
tra\elleii  in  the  same  path,  upon  the  diversion  of 
the  stronj^er  stimulus  into  a  new  pathway.  It  is 
well  known  that  stronjr  stimuli  often  hreak  over 
into  additional  pathways  of  discharge,  and  it  is  of 
course  possible  tb.it  such  a  phenomenon  might  occa- 
sion a  re\ersal  of  reaction. 

What  part  the  inhibitory  intluence  of  stirm-l  nay 
play  in  reversal  is  uncertain,  l.oeh  has  allu  to 
the  possible  role  of  this  faaor  in  one  of  his  e..rlier 
papers  (V>.^),  init  without  developing  the  suggestion 
further.  When  an  earthworm  turns  away  from  the 
light  we  may  assume,  as  in  fact  has  been  done  by 
Davenport  ('';7).  that  the  action  of  the  muscles  on 
the  more  illuminated  side  is  inhibited,  and  that  the 
animal  accordingly  turns  away  from  the  stimulus. 
1  here  is  no  e\  idence,  howeve.-,  that  such  an  inhibi- 
tory process  occurs.  A  worm  turns  violently  away 
when  one  side  is  touched  with  a  hot  needle,  but  the 
movement  is  not  due  to  the  mere  inhibitory  effect 
of  the  stimulus.     If  the  turning  away  from  the  hot 


1 14 


Siitdit.s    in   .tiiiithil   Itilnni'if 


ihiilli  i-.  ilur  t'l  the  i(intr;utiiin  ot  tin.-  Iniijfitmlinal 
iiiiimIis  oI  iIr-  dpixiNik'  siilf  <>t  the  hiuK  <mt  woulil 
M.ifiii.illv  •suppose  th.it  th  .i\(iiihiiKc  ••!  a  h^ht  was 
I'inii'jht  alxiut  in  the  same  way. 

\  i^^\  \ears  a^c  I  endeaxiiiii  to  study  the  pos- 
Mhle  iiihihitMrs  etteit  <>l'  li^lit  in  tile  phdtotaxis  of 
\(tlvi>\.  It  the  orienlatinn  'it  N'oKox  when  swirii- 
iiiiii^  liiu.iril  tlie  li;^!)!  i-^  ihie  tc  th;  tatt  that  li^^ht 
t(  rills  hi  itihihit  the  aitmn  nt  the  tIaLjella  on  the 
mure  stiuM;^l\  illiimm.iteil  sulc,  ue  shnuKI  expeet 
lliat,  as  the  ni'Ljamsm  passed  I  rom  a  region  i)t  liini 
li'jlit  ti)  wliefe  the  li^llt  was  more  intense,  its  gen- 
eral rate  ot  hu  Drrintmn  uouhl  ileerease.  since  !>oth 
^'iles  wi'uKJ  he  more  stniiiLrK  afteited  In'  the  mhihi- 
t<i|\  siiiiiuliis.  Speiimens  ol  \  oK  ox  were  placed 
in  a  '^lass  troiii.;h  the  Imitom  o(  whieh  was  markeil 
oH  iiUo  eijiial  s|>ai.es.  I  he  time  rei|uired  tor  a  speci- 
men to  tia\eise  eaili  spaee  in  its  course  towanl  the 
liL'ht  was  iiiited  if)  a  number  ot  eases,  and  it  was 
toiind  that,  on  the  average,  the  speed  ot  the  or^an- 
isiri  was  ijuite  uniform  in  the  varying  intensities  of 
li^ht.  I  he  \  oK  ox  swam  with  much  the  same  rapiil- 
■t\  mitil  rhe\  came  near  the  optimum  when  their 
IWi.-!.'  heijan  to  slacken.  I  he  results  ot  the  experi- 
ments were  therefore  opposeil  to  the  \  iew  that  orien- 
tation is  effected  !>\  the  inhihitorv  effect  of  li^ht  on 
llie  mo\ements  nt  the  'lamella  on  the  more  illumi- 
Ti.ited  side  ot'  till-  ori^aiiism.  Inhihitioii  may  function 
in  other  wa\s  'u  t!ie  orientatioti  of  \'ol\ox  and  in 
c!i.mL,'inu  the  sense  ot  its  reactions  to  lij^ht  and  other 


'/'/;/■    Riirruil   "f    7'> '/>;'•"> 


1  I 


t.inn>  <<i  stiiiuil.iti.iii.  I  Iki'c  is  mih  li  to  iii>lu.itr  tli.it 
'mliibititm  is  ituimati'ly  rclatrii  ti>  ic\un,iI  <'I  tr<>- 
pisms  in  many  \<>vm-.  Init  I  shall  iiui  \iiitiirc  up.ni 
anv  spi-culations.  uliiili  at  !>isr  o>iiKl  "nK  In-  \  i  i  \ 
rciitati\(.-,  as  tu  its  mitlio  1  nt  opuMtinn. 

It  is  (|uit(.'  piissiliK-  that  thi.'  explanation  ol  i\  \  i  is.tl 
of  tropisins  may  hf  M"''^'  *iit'i''*-'"t  i"  ^liHrtcnt  ^  .1  i  s 
Many    rhi/opnds   show   a   pi'sitis..'    thii,rm«>t;i\is   t..   .1 
weak  mechanical  stimulus,  uliih'  tlu\  ^\\i'  a  n,^ati\i- 
reaction  it'  the  stimulus  is  stronjx.      Is  this  to  he  i  \- 
plaincci  in  th.'  same  way  as  the  reversal   iti  the  l>e.it 
of  the   tla^ellum  in  a   llai^rdhur,  or  ot'  the  cilia  in  an 
intusorian?      Aiui  iloi.s  .uu   ot   these'  ea^es  have  an\- 
thinji;  in   eoiiunon    with  the    revers.il    ol    tropisins    m 
an    insect    or    worni."       I  he    meehanism    ot    orienta- 
tion is  (Uiite  ditterent   in  ilittcreiit  or^^anisnis,   .iiul   it 
seems  not   improhahle  that  the  inner  meehanism   ot 
reversal  mav  he  \ery  iliHerent  also,   alihoui/h  there 
mav  be   hroad   utulerKin^    features    common    to   nu- 
merous a|iparently  ditterent  eases. 

L  p  to  the  present  lime  most  ot  the  uoik  on  the 
reversal  of  tropisms  has  been  done  with  a  view  ot 
ascertaining  the  varueis  eondilions  under  uhich  re- 
versals mav  oeeur.  Main  mte|•estin^  taet--  have 
been  accumulated,  but,  as  we  have  seen,  they  altoiil 
no  very  sound  basis  for  ^eiierali/ation.  We  shall 
make  little  further  progress  In  im  re  induction.  We 
need  to  feel  our  way  alon<4  bv  m.ikinj:;  hypotheses 
and  testinji  them  by  approi)riate  experiments.  i5ut 
when  one  attempts  to  attack  the  problem  in  this  way 


ii6 


Sliulifs  in  .Juimul  Bchinior 


he  soon  limis  himself  hampered  by  the  paucity  of 
kno\\lcdji;e  in  those  tieKls  to  which  fie  wouKl  naturally 
turn  for  helpful  suggestions.  It  wouUl  he  \ery  ile- 
sirahle  to  ha\e  a  more  ailci|uate  knowledj^e  of  the 
inner  mechanism  of  orientation.  It  would  be  very 
helfiful  to  have  a  deeper  insi,u;ht  into  the  physioloji;y 
of  irritability.  We  know  little  of  the  processes  cov- 
ered by  the  wortl  stimulation.  We  are  still  lookinjj; 
for  a  satisfactory  explanation  of  the  curious  phe- 
nomenon of  inhibition.  The  beha\iorist  may  disco\  er 
many  facts  of  interest  and  value  re^ardinjj;  the  re- 
versal of  tropisms,  but  before  arrivinpj  at  an  ade- 
(juate  explanation  of  this  perplexinp;  phenomenon  he 
m..y  have  to  wait  until  some  of  the  more  p;eneral  ami 
fundamental  problems  of  irritability  ha\e  been 
solved. 

HKFFRF.NCFS 


B.\N(.'K(H'l',  v.  W.  (  1  )  The  control  of  jralvano- 
tropism  in  Paranurcium  by  cb.emicals.  Univ.  of 
Calif.  Pubs.  I'hysiol.  3,  21,  1906;  (2)  Ileliotro- 
pisrn,  etc.,  in  luiglena.     Jour.  F'.xp.  Zool.   15,  3S3, 

Haui.k,  \'.  I'eber  die  retlcktoriiche  Rejfulie- 
rung  iler  Schwimmliewegun^cn  bci  den  Mysideen, 
etc.     /eit.  allg.  Physiol.   S,  34:?.    iquS. 

Holix,  (i.  La  naiss.mce  de  I'intellijfencc.  Paris, 
1909. 

DwiN'roKl.  C  H.  I'xpeiiment.d  .Morpholoiiv. 
N.  V...   1^97-99- 


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1  sriKi.v,  C.  O.      Reactions  of  copcpods  to  li^ht 

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(,K<M»M,  T.  v.  and  I.oi.H,  J.  Dcr  llcliotropis- 
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IlARl'KR,  I'..  II.  Behavior  of  the  phantom  larva 
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lIoi.Ml.s,   S.   J.      (i)    Phototaxis   \n  the   Amphi- 

p,,da.  Am.  Jour.  Physiol.,  5.  211,  \iy>\\  (2)  Pho- 
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\cur.  I'sych.,  15,  305,  1905;  {4)  '"li^  reactions  of 
mosciuitocs  to  lij,rht  in  different  stajj;es  of  their  life 
history.     Jour.  Animal  Behavior,   i,  29,   191  i. 

JACKSON.  11.  n.  I'.  rhc  control  of  phototactic 
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l.oi  1;.  ].  Leber  kunstliche  L'mwandlung  positiv 
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M.\sr,  S.  ().  (1)  I-ight  reactions  in  lower  or- 
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I  I  ^ 


N///i/.'i  >    ///   ./iiiiiiiil   liihailur 


iSycli..  ly.'v;,  i'>"7;  (2)  I.igfit  arul  tlic  hch:i\  ior  of 
di-^aiiisnis.     \.   ^  .,    1911. 

Mi(il\\|s,  M,().  Reactions  (it  Brancliipus  scr- 
r.itus  to  liLi;lit.  litat  ami  ;^ra\ir\.  jour.  I'.\[).  Zool., 
I ' '.   ii~ .    I  '>  I  i . 

MooKi  .  \.  K.  II)  (.  oturmitiLj  rH'|xati\>.'  photo- 
trupiMii  in  Daphiiia  pulc\.  Jour.  l.\[).  /ool.,  13, 
s7i.  I'M  2;  (2)  Negative  [iliototropiMD  111  Diapto- 
1111!^  !n  iiuans  dt'  str\  iluiinc.  I  niw  ot  C  alit'.  Pubs. 
I'li\  sidl..  4.    I  S  :;,    I  ly  I  2. 

AI<|<|'<|.  1».  '  )hsLr\  ations  of  certain  marine  or- 
;j;anisi)is  ot  (a)  '.  ariatious  in  reaction  to  li^ht,  and 
( I1 )  ilitirnal  peiimluitN  ol  pho^pliorescencc.  Bio- 
elieiiiual   jour.,    4,    1,    nyn^. 

l'\KKl  II,  (1.  II.  i\eaetions  ot  eopepoils  to  \ari- 
oi;s  stimuli  aiul  the  hearing  ot  tliis  on  their  daily 
depth-mini  .itions.  Hull.  l.  S.  I  ish  Conuii.,  21,  11J3, 
|(yi<l  . 

I'l  \i\i.  R.  I  lie  mo\  emeiits  and  reactions  of 
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^'i(>,   i<;i'3. 

SiK\s|;i  K(,rK,  I'.  Die  Wirkutiii;  des  Lichtes  uiul 
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;7  2,  1N7S. 

I  1  Kin,  (  ).  I'.  ( i.d\  anotro|Msm  ot  X'ohox.  Am. 
jdur.  I'!i\  sidl.,  1  ;,  23  ^.  1  (ji)6. 

I'^wil.  1  .  A  study  in  the  heliotropism  of  Cy- 
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\lK\\iiK\,    .M.       (leiieral    phvsioloi^v.       London, 


Rifiri'tici-s 


119 


Vi.RKis,  R.  M.  Reactions  of  cntoinostraca  to 
stimulation  by  liRht.  H.  Reactions  of  Daphnia  and 
C'ypris.     Ani.  Jour.  Physiol..  4.  4*'v    ">'»l- 


VI 


Mil      i:i(;iNMN(iS    Ol      INI  I.I.I, Kii, MI, 


N 


()rilIN{i  sIk'ws  more  rhc  force  c)f  habit  in 
reconciling  us  to  anv  phenomenon,  than  this, 
that  men  are  not  astofiishM  at  the  operations  of 
their  own  reason,  at  the  same  time,  th.at  they  ad- 
mire the  insliint  of  animals,  and  find  a  ilitficulty  in 
explaininLT  it,  merely  because  it  can  not  be  reduc'd 
to  the  \er\  same  princi[)les.  'i'o  consiiler  the  mattei 
arif^ht,  reason  is  nothinij;  but  a  wonderful  ami  un- 
intellijrible  instinct  in  our  souls,  which  carries  us 
alon^  a  train  of  ideas,  and  endows  them  with  par- 
ticular (]ualities.  accorilinjf  to  their  particular  situa- 
tions and  relations. — l)a\  id  1  lume,  Treatise  on 
I litwan  Siilnrc. 


We  all  ha\e  a  certain  curiosity  icp^ardinj";  the  evo- 
lutionary history  of  our  various  powers  and  attri- 
butes, but  from  many  points  of  view  an  unusual 
interest  attaches  to  the  lirst  de\elopment  of  intelli- 
<,H'ncc.  1  he  word  intellip;ence  is  used  in  a  \aricty  of 
senses  by  writers  on  comparative  psychologv,  and 
any  tliscussion  ot  the  origin  of  intelligence  would 
be  truitless  unless  the  meaning  in  which  the  term 
is  employed  be  understood.     One  of  the   foremost 

120 


Till'  Rcg'mmnijs   of  bu^U'ujntcc 


121 


ot  comparative  psycholojrists,  the  acute  lather  W  as- 
niann.    detines   intel!  _;once    as    "the    power   of   con-; 
ceiving  the  relation  of  concepts  to  one  another  and  i 
of  drawinji  conclusions  therefrom.      It  involves  ab-  , 
straction,   deliberation    and   self-conscious    activity." 
Intelligence,    accordin.u;   to   Wasmann.   is   the    dod- 
given  attribute  of  man  alone;  its  possession  separates 
man  from  brute  1  .    an  impassable  barrier. 

Many   comp:irative   psychologists,    among   whom 
uc  may  mention   Lloyd    Morgan,    I'orel   and   I.<ieb. 
adopt   as   a   criterion   of   intelligence   the   power   of  . 
forming   associations,    or      -sociative   memory,    and  ' 
we   shall    follow  the   usage   of  these   writers.      It   is 
obvious   that   the   possession   of   this   faculty   marks 
an   important   step    in   advance    upon   the   creatures 
whose   acticms   are   fatally   determined   bv   their    in- 
stinctive make-up.     I'rom  its  beginning  in  f(Ji;ns  m 
which  the  simplest  associations  are  established  only 
after  a  large  number  of  experiences,  intelligence  has 
assumed    a    role    of    ever-increasing    importance    in 
the  evolution  of   animal   life,  until   in  inan,  who  is 
notoriously    a    weakling    compared    with    the    large 
beasts  with  which  he  has  had  to  contend,  it  became 
the  main  factor  to  which  ihc  human  species  owes  its 
suprcmacv   in  the   struggle    Mr   existence. 

In  considering  the  origin  of  intelligence  one  is 
naturally  led  to  the  subject  of  the  relation  of  in- 
telligence to  instinct.  Formerly  it  w.i>  the  custom 
to  contrast  these  two  faculties  as  if  they  represented 
diametrically  opposed  types  of  acti\  ity.     Instinct  was 


122 


Sii,(Jifs   in   .hiiinal   lithavior 


rcf,Mrtifcl  as  something  unaltcralily  tixcil,  jnacliinc- 
likc  ami  practically  perfect  in  its  ailaptation  to  the 
neetis  of  the  animal:  intellifjence  was  recojrni/ctl  as 
the  antithesis  of  all  tlie>c  (jualities — sariahle,  plas- 
tic ami  eiiiinentlv  fallihle.  With  the  establishment 
ot  the  theory  ot  exolution  writer:,  became  more 
ilisposed  to  ilisco\er  the  kinship  arui  filiation  of  in- 
stinct ami  intelligence  ami  tluy  lia\e  ^i\en  us  a 
\ariety  ot  \ieus  as  to  the  relation  of  these  facul- 
ties. 

Basing  liis  theory  on  F.amarck's  doctrine  that  in- 
stinct is  inherited  habit,  (i.  11.  I.ewes  attempted 
to  explain  instimt  as  "lapseti  intelligence."  P't- 
lormances  which  are  learned  with  ditliculty  come, 
after  sutHcient  repetition,  to  he  carried  out  auto- 
matically ami  witluuit  am  intelligent  j,midance.  If 
the  aci]uired  facility  of  performing  these  acts  is 
inherited  ami  the  acts  are  repeated  generation  after 
^reneratioti,  it  is  [irobable  that  they  mi^rht  tinallv 
fie  }>erlormed  by  an  individual  without  any  previ- 
ous instruction  at  all;  that  is,  thev  would  become 
instinctive.  An  animal's  instincts,  accordinjj  to  this 
view,  represent  the  stereotyiKnl  and  mechanized  be- 
havior  which  its  ancestors  fouml  to  be  profitable; 
their  adaptiveness  rests  upon  the  wisdom  ac(]uired 
bv  amcstral  experience.  .More  recently  this  view 
has  been  upheM  b\  I'imer,  ,ind  in  a  less  extreme  form 
by   Konianes,   Wundt  .\m\  m:inv  others. 

One  difHcuItv  with  the  theory  of  lapsed  intelli- 
<,^cnce  IS  that  it  involves  the  acceptance  of  the  iloc- 


■/'/;<■    ntt/niniii/."    "/   I ultUujnii 


'^3 


triiic    ot'    the    iransi'.issiiin    ot    ;K(|iiircil    cli:ir;ut(.'rs,  j 
which  has  loiik-  to  he  a  wry  .|ui.sti<)nah!c  hi<>h>^iical  ■ 
thiory.      lUit    another    ami    more    tuiuiameiital    ilit- 
tieultv  is  re\ealeii  hv   recent  work  on   the   iK'havior 
n\  lower  orjraiiisins.      It'  instinct  were  deriveil  from 
intelligence    by    a    sort    of    mechani/iny;   process    we 
should   expect,   as  Whitman   has  ur^eil  in   his  criti- 
cism  of    l.ewes's   theorv.   to   linil   intelligence   domi- 
nant in  lower  forms  of  life,  ami  that  acts  which  are 
instincti\e   in   the    hii,dier   animals    would   be    intelli- 
^cntlv    performed   by    the   lower  ones.       1  he    work 
that   has  been   done   on  the  behavior  of  lower  or- 
i,ranisms   enables   us   to    state    with    confidence   that 
such  is  not  the  case.     In  several  large  phyla  of  the 
lower    invertebrates    there    has    not.    as    yet,    been 
demonstrated  the  least  glimmer  of  intelligence;  and. 
as  we  pass  up  the   scale  of  life,   intelligence  grad- 
uallv  supersedes  instinct,  not  the  reverse.     We  can 
say   with   some   degree   of   assurance   that,    however 
the    transition   may   ha\e  been   eHecteii,    intelligence 
has  grown  out  of  puretv  instinctl\e  behavior. 

It  is  not  possible,  however,  to  fix.  except  with 
the  rudest  approximation,  the  stage  of  evolution  at 
which  intelligence  makes  its  first  appearance.  I'hc 
transition  from  instinct  to  intelligence  has  been 
made,  in  all  probability,  not  once,  merely,  but  sev-  ' 
eral  times  along  ditierent  lines  of  descer.t.  Intelli- 
gence in  the  \ertelirates  doubtless  arose  independ- 
ently from  that  of  the  inserts,  and  the  intelligence 
exhibited  here  and  there  among  the  moUusks  prob- 


124 


Sltulirs  in  .hiimal  Bi'luninr 


;iliK  ;iri>si'  imiipi.nil'jntly  aloii^  a  thiril  line  of  dc- 
\  ildptiKiit.  Intclli^ciuc  makes  its  appearance  at  a 
tert.iln  sta^e  ot  or^ani/arion  alnny  whatever  line 
sutli  a   staj^e  ina\    have  luen   reatheJ. 

I  p  to  tlu'  ]ioiiit  at  which  the  power  of  assncia- 
ti\e  inemorv  heeomes  tiiaiiitest  there  has  heen  prog- 
1  e'^s  ahm^  m  inv  lines  which  has  prepareil  the  way 
tor  the  ixohition  ot  this  new  faculty.  Heha\ior 
has  iMt  onlv  heiome  more  complex,  Init  it  has  bc- 
mme  more  p.lastic  ami  capable  ot  easv  miuhlication 
to  suit  new  conuitions.  I  he  lower  organisms  do 
not  alwass  react  in  a  particular  way  to  a  jri\cn  stim- 
ulus. What  reaction  occurs  mav  tle})en(.l  ii[)oii  the 
num'.H'r  ot  ]ire\  'ous  stimulations,  the  sujiplv  of  food, 
exposure  to  ilitterent  environing  conditiotis,  and 
numerous  other  t actors  which  inliuence  the  internal 
state  ot  the  orj^anism.  I  he  beha\  ior  of  many  lower 
animals  is  plastic  and  adaptive  to  a  reriiarkable 
decree,  ami  to  a  superficial  consideration  often  ^ives 
the  appearance  ot  a  considerable  tlej^ree  if  intelli- 
gence, without  there  beiii^  any  iletectable  power  of 
associativ  e  memory.  I  his  plastic  and  varied  bc- 
havior  not  only  simulates  intelligence,  but  it  se- 
ures  tor  the  (Uranisms  manv  of  the  ad\  antapjcs 
which  intelligence  confers.  It  adapts  tlie  animal  to 
a  moi'e  \arieil  enxironment,  and  ^i\es  it  the  power 
I't  meetinf:;  a  given  situation  in  more  than  one  way, 
so  it  one  kind  of  response  does  not  suit,  another  may 
be  more  successful.  Let  us  glance  brieHy  at  some 
ot  the  ways  in  which  behavior  may  be  modified. 


Till'  lii-gintnuijs   of   liiliHi(/rn.  r 


I  2 


A    \cry    ^ciiLTal    cluinm.'    ot'    iHli.nn.r    in    or^i.in- 
Isnis  consists  in  the  habituation  to  any  stimulus  uhiJi 
i>  rcpcatcJ  at  sufficiently  close  intcr\aK  v.  that  the 
(U-^anisni  no  lonjj;er  responds  to  it.      I  lus  is  ^h.  am 
rvcn  anion^r  the  proto/oa.      A  Stcntor  or  a    l.o\o- 
phylluni  suhjectctl  to  a  li^ht  mechanical  stimulus  at 
short  intervals  soon  tails  to  respoiul  as  at  tirst.  but 
the  duration  of  the  moilitication  so  (M-oduccil  is  \cry 
short;  in  Loxophyllum  it  probably  docs  ni>t  extend 
nver  two  or  three   seconds.      Similar  ettect-,;   ot    re- 
peated stimulation  but  of  lonj^cr  duration  ha\  e  been 
observed  in  Hydra,  several  species  of  sea-anemones, 
planarians,  annelids  antl  \arious  other  lower  mver- 
tebrates.      .As  a   rule   failure  to   respond  may  occur 
more  ([uickly  and  the  eftects  of  the  stimulus  remain 
lonjrer  as  we  pass  up  the  scale  of  animal  life. 

Occasionally  the  reverse  phenomenon  occurs 
when  the  response  to  a  given  -..timulus  is  increased 
instead  of  diminished  with  repeated  applications — 
a  result  which  suj^gests  the  effect  of  the  summation 
of  stimuli.  .\t  times,  as  Hohn  found  in  C'erianthus, 
there  is  an  initial  increase  of  responsiveness  tol- 
lowed  by  a  dulling  of  sensitivity.  Hohn  has  at- 
tempted to  subsume  the  effects  of  repeated  stimula- 
tion under  a  general  "law"  to  the  effect  that  stimu- 
lation always  produces  at  first  increase  of  sensitivity 
to  be  followed  later  by  a  decrease.  Sometimes,  as 
Hohn  claims,  the  initial  increase  is  so  short  as  to 
escape  detection;  which  may  be  t.  -e,  but  the  burden 
of  proof  is  on  M.  Bohn. 


126 


Sill, ill  <■    III   .Ininiiil    liiliiiiior 


Kc'iKtirioii  (it  a  stimulus  mav  lall  tortli  not  dtily 
(]uaiititati\  c  di  Here  litis  ol  rcspnnsc,  Init  it  mav  c\(»kc 
rospdiisrs  lit  \crv  dittcrciir  cliaractcr.  Aiumals  arc 
t  rciiucntiv  pnu  iiKil  with  several  modes  ot  reacting 
to  a  ^i\cii  stiiiuilus  uliieh  may  he  ealled  into  play 
one  alter  the  other.  JeiuiinL^s  has  shown  that  it 
a  Stentor  is  suhjecteil  to  a  li^lit  meelianii.al  stimuhis 
by  causinjr  line  particles  ot  India  ink  to  tall  upon 
its  disk  Irom  a  lapillarv  pipette  it  u^ualK  reacts 
first  h\  hiniliiiLi;  a  little  'n  one  siili-.  it  the  paiti- 
eles  continue  t<i  tall  on  the  disk  the  heat  ot  the 
eil::i  coverinj^  the  Ixulv  mav  suddeiiK  he  reversed, 
thus  creatiiifi  a  current  tendmji;  to  carrv  the  ottend- 
in^  particles  away,  it  in  spite  ot  this  the  particles 
still  iiiipinj^e  upon  the  ilisk  tlie  .Sttntor  mav  con- 
tract one  or  more  times.  I  inally.  it  all  these  re- 
actions are  trieil  in  vain  the  intusorian  may  j;ive  a 
number  ot  violent  contractions,  break  loose  from 
its  place  ot  attachment,  ami  swim  awav. 

It  woulii  be  an  error  to  interpret  the  varied  be- 
havior ot  this  unicellular  ori^anism  as  a  manitesta- 
tion  ot  intelligence,  althou;j;h  it  is  not  unlike  what 
the  behavior  ot  an  intelligent  creature  mi^hr  be 
under  tlie  circumstances.  No  [)ovver  ot  learning  by 
experience  has  ever  beiii  discovered  in  Stentor,  or 
indeed  m  any  other  proto/oan.  I  he  ortranism  is 
|irovitled  with  a  number  ot  ditlerenr  modes  ot  re- 
sponse, and  which  one  is  set  in  actioti  depends  upon 
intern. d  tactors  which  are  intluenced  bv  the  crea- 
ture's previous   activity.       The  organism   which   has 


I  «  ■     _J  v^  »    I     ^^  .^    VJ  —t^s^  I  ^J~ 


Till    Rit/iuiiithfy    "/   lull  lliifini  r 


1^7 


rf->pi)iuitvl  to  a  stimulus  has  l>ou)nu-  traiistdrnuil 
Into  a  dittcrciit  mechanism  which  may  rcspntul  mure 
i.r  liss  naiiily  than  hctorc  or  railically  ihaii^c  its 
iiuthoil   ot    behavior. 

\  striking  illustration  of  varicil  responses  to  a 
.riven  stimulus  has  been  ilescribed  by  Jennin^'^  in  the 
sea  anemone  Stoiehaetis.  If  a  forei>,ni  body  is  plaeej 
upon  its  disk  the  anemone  tries  to  rid  itself  ot  the 
obieet  in  \arious  ways.  The  tcntaeles  near  the  ol>- 
iect  collapse  ami  the  area  between  them  extends, 
thus  producing  a  relatively  smooth  surface  so  that 
the  waves  can  readily  wash  the  object  away.  If  this 
does  not  occur  the  region  uiuler  the  object  beyitis  to 
A  ell,  thus  renderinji  the  removal  of  the  object  stdl 
easier.  If  this  reaction  is  unsuccessful  the  ed^^e  of 
the  disk  begins  to  sink  so  that  a  smooth  sloping;  sur- 
face is  formed  from  which  the  object  can  readily 
slide,  llere,  as  in  the  case  of  Stentor,  we  ha\e  an 
(irir;inism  capable  of  reacting  in  several  ways  to  a 
^i\en  stimulus.  What  particular  reaction  is  evoked 
depends  upon  previous  stimulations. 

Moditications  of  behav  ior  causeii  by  ditlerent  con- 
ditions of  nutrition  are  fouml  in  the  lowest  mem- 
bers of  the  animal  kinj^dom.  I'.ven  the  white  blooii 
cells  after  they  have  ingested  a  number  of  bacteria 
refuse  to  take  in  more.  Whether  there  is  a  limit 
to  the  appetite  of  Amirba  has  not  been  determined, 
but  many  infusorians  such  as  Stentor,  after  having 
swept  in  a  certain  amount  of  food,  react  to  fond 
particles  in  a  (juite  dlfierent  way  than  when  in  a  hun- 


I2S 


.Sll,}l.  HI       llllllhll     //<  Ihl^inf 


iiv\  inriilitiiiM  llv.lii  wl'iii  iinf  till  ti>r  ^iiinr  t;iiu' 
ivtniils  till  I'liiK,  s\s,i\s  ;il<iiiif  in  \.iriniis  iliii.-i. tioiis 
:iii|  klips  up  :i  ri'stliss  muviiiunt  i>\  its  fi  iit.ii  Ks. 
tlliTtln  Ilk  iwlsill^  its  ill.linis  (it  miit.Ut  \K\t\\  till 
siiiiill   (  rr.if  iiris   uhuli   sir\c   ;is   its   pnv. 

Inst. nil  IS  (i(  tlir  iH  ininti  lli^iiit  mdiiiliiiitiniis  of 
luli.M  iiif  init;lit  I'f  niiilf  ipl'i'tl  iiiilihnitrK  .  \s  u  r 
|>.iss  tip  lll^lll■^  Imins  t'u-  i;ip;uit\  lui'  l^splllhiln^  in 
ililtirrnt  \\;i\s  tn  :i  u'iniii  sitiiiitii'n  h'liiinrs  tiPiMtU 
ifuri;isiil  "\  .itiiii."  s;i\s  jauirs  in  !iis  :iilniir.i!>li' 
tli.i|>tir  (in  in--tinit.  "inipl.inls  uMitiMix  nnpuKcs  tu 
•at  in  m.iiu  rl:isMs  nt  iliiiii^s,  ;in.|  Ii,i\rs  it  to  slight 
•  ilt.T.it.iins  III  till  ,  I  iMilitmii-,  111  tin-  niiliv  iiiiKil  .isi' 
tu  iliiiilf  wliuli  iinpuUi  shall  i.iri\  tin  ilav,"  aihl 
jlii-  piiinls  (Hit  that  nian\  animals  Insi-  tin-  instiiutiv  c 
lii'nuaniir  aiiil  appiar  tu  K-nl  a  lik'  ot  lusitatiun 
:unl  ilmur.  not  luiausc  tlu  \  ha\f  no  instiiuls,  hut 
hi'iausr  tlii\  lia\r  mi  main  nt  rlinii  that  tlii\  Mmk 
ruu-  aniitlur's  path.  jntillii^i.  m  i-  m  rlic  acctpta- 
tinn  111  the  tirni  wliiJi  w  i'  ha\i'  aJnpti'il  hi^ins  with, 
till'  ti'Vtnatiiiii  lit  as,iu  latiiiiis.  [t  .Id.  'Mt  inai.;  it'^ 
apfii'a  ram  r,  mi  tar  as  is  knnun,  until  a  h'Mj  ara.- 
ti\il\  lii^h  staler  lit  iiri^an; /atiiiii  has  h^'i'ii  attaitiiil 
I  111'  ivnlutiiin  aliinu  thi'  liius  nt  iiimplr\ii\  nl  iii- 
stinit  ami  rraiK  niiulitiahilits  nl  rractiniis  to  suit 
new  lomlitions,  attorils  a  suhstantial  basis  tor  in- 
ti'lliLjrnt  lu'lunior.  W'itlionr  smh  evolution  thf 
power  ol  asMiiiatixc  iniinorv  uoiiKJ  axail  littli'. 
I^iir  wit!)  a  larLji'  nutnhrr  ot  rraiiilv  iniuliliaSIr  in- 
stiruts.    assi  K  iati\  r    minior\    hci  onu's    tlir    nuans   ot 


I'll,     /)'.  ./iiniiih/'    "j    lii(>  /.'"/>  "'  <• 


\l<t 


.itt.iiJ'iiii:    .1    miuli    ui'Kr    .111.1    JoMi-    .uljuslmuii    I" 
t!u-  iM\  irtui'iu  lit. 

IIk'  sru.lit-.  uliiil'  li.iM-  li'iii  miul^  "t"  piimitnc 
t\i-is  i.t'  'mti!li^itu<  Muii  .1^  ti-un.l  in  v  lust.uiMns, 
ll^llt■s  aiul  ;implii!'I;ins  liaxi-  slmMi  lli.it  .ismh  ial'miis 
,ii\'  I'dniu'il  In  ,1  m-,ulu.il  pi-diiss  III  rcint'TirmiiU 
..r  iiilul>iriim  ot  .i  p.irtiuil.-r  riMitimi  t<>  .i  ^'im-m  stiiu- 

llhlS.  riu-     lIKlhuvl     'I'lliiUcd     is     'MK'     'Vllii'l      I   \>'\d 

.Morgan    \v.\s   disi|^naU'il   as   "trial    aiul   irror."      It 
MMv  1h'  illiistratiJ  liy  tlu'  i\|)i.riiiu'nt  ol    dirk's  oii 
till,    fnrinaticn    nt    assotiatinns   in    tlu'   iraylisli.      In 
ihisc    txpiTimonts    a    box    was    inii'l'iN  iil    ii.tn    "mi.- 
uul  i<\    wliitli   till'  craytisli   was  aiimittrd  tliiiiii;,r|i   a 
narrow   aperture.       I  he  otlicr  inil   nt    tlic   liox   was 
-livided  liy  a  iiiciiian  partition  uliirh  ^a\i'  the  (  iay- 
li-h   a   clioiei    n(  two   routes   to  a   tan\   "•    w.iter   at 
the  ottiei      '1  i  into  uhiih  the  ere.Uure  was  natur.ilU 
ilesirou.-;   of   ireitin^.      f  >ne   nt    the   two   uavs   to   the 
water  was  eloseil  In   a  ijlass  plate  at  its  f.'-ther  enil 
so  that  the  eravlisli  was  atti)rile.l  a  ehoiee  ol   a  riL;ht 
nul  a  wron^  path  to  the  water.     W'ouM  the  eravlish 
alter   a    luimltcr  oi'   tri.ijs   ie.ir:-   •      ehoose   t!ie    n^'ht 
pat!)  anil  a\(iiil  the  eloseil  passage:*     In  the  first  ten 
lAperiments  the  iiaylish  went  as  otten  to  the   rij^ht 
as  Ir  dill   to   the   left,   hut   in   the   next   ten   trials  the 
|iereentai;e  ol  eorreet  ehoiees  was  somewhat  greater. 
I  inally    alter   a    laru;e    nuniher   ol    triaU   tfie    aniiii.il 
eame   to  ehoose  the    rj^lit   path  to   the  water,   m.ik- 
in^  hut  r.irelv  any  mistakes. 

Similar    experiments    with    erali>.    'ishes    ami    the 


'3" 


.S ///(//(  5   /■//   .l)iiiniil   BthdVhir 


IroLC  lia\i'  \i(.-liK(l  similar  indicatio'is  of  slow  learn- 
ing. In  sonic  respects  siuli  learning  rcsniihlfs  the 
slow  tiii-ni.'tion  ot  a  habit  rather  than  the  jiui^inent 
lit  a  eonseidiisness  whieh  "si/es  up"  the  situation  and 
ilete"mines  u[ion  a  eertain  course  ot  action.  It  is 
i|uite  prohahle  that  such  a  primitive  torni  of  learn- 
ing lioes  not  iruUule  anv  association  ot  ideas.  it 
can  he  satist actorilv  accounted  tor  h\  assumnit^  noth- 
ing more  tlian  an  association  of  ceitam  sense  per- 
ceptions with  particular  niovenicnts.  I  he  animal 
mav  ha\e  no  ideas  to  associate — nothinjr  hut  sense 
impressions  antl  motor  impulses.  <  )f  course  its  men- 
tal content  iiicix  inchule  much  more  tlian  this,  hut  in 
interpreting  the  hehasior  of  animals  it  is  generally 
ad\anta^eous  to  tollow  the  jirinciple  laid  lionii  hv 
i  lovd  Morj^an — winch  is  a  sort  ot  sjK'cial  ap[)li- 
cation  of  the  law  ot  parsimony— that  we  sliouKl  not 
assume  the  existence  of  a  higher  psvchic  function 
it  the  phetioinena  can  l^e  explained  as  well  in  terms 
ot    a    lower  one. 

I  he  ste[)  from  sensori-rrritor  association  to  the  as- 
sociation of  iileas  IS  not,  I  believe,  a  wide  one,  and 
comes  about  as  a  natural  consequence  of  the  elabo- 
rateness and  what  I  lobhousc  has  designated  as  the 
"articulateness"  of  the  mental  process  of  atliiistment. 
It  is  toreign  to  our  purjiose.  however,  to  trace  the 
iiurease  in  the  number,  delicacv,  (]uickness  ami  com- 
plexity ot  the  processes  ot  association  whicii  we  meet 
in  the  \  arioiis  stages  ot  mental  e\  ohition.  '  )ur  prob- 
lem .It  present  lies  in  the  initial  step  in\o|\cd  in  the 


Tlu-   Hiijinm}uj>    "f   IntcUujiiuc 


'3' 


toniuition  ot  ;i  siinpK'  association.  Aiul  it  is  a  prob- 
lem which,  .Icspitc  its  apparent  .imphntN.  involves 
t!ic  consideration  of  some  vexed  aiul  suhtle  ques- 
tions. 

In    learnin-    we    have    to    do    uith    two    opposite  j 
processes  of  reinforcement  ami  inhibition.     A  chick  '■ 
after  it  pecks  at  a   caterpillar  which  is  wholesome 
and  savory  pecks  at  a  similar  caterpillar  more  read- 
ily on  a  second  occasion.     Something  has  apparently 
reinforced  the  connection  between  the  visual  impres- ^ 
sion  produced  by  the  caterpillar  and  the  pecking  im- 
pulse.     If,  on  the  other  hand,  the  chick  pecks  at  a  ^ 
caterpillar  having  a   nasty  taste  it  is  apt  to   avoid  ' 
pecking  at  it   a  second  time.      Somethin<;  has  hap- 
pened to  inhibit  the  response  that  would  .)therwise 
occur.      We    commonly    explain    such    behavior    by 
uscribiik^  to  the   creature    feelings   M   pleasure    and 
pain.     We  say  that  the  chick  pecks  at  one  k'.nd  of 
a    caterpillar   because    of   the    pleasant   taste   it   de- 
rives,  and  avoids  another   variety  because  its  taste 
is  bad.      Pleasure  and  pain   apparently   function   as 
agents    for   the    reinforcement   of   certain    reactions 
and  the   stamping   out  of   others,      it   is   a   general 
rule,    though    not   without   certain    exceptions,    that 
what  artords  pleasure  is  conducive  to  organic  wel- 
fare, while  that  which  is  productive  of  pain  is  in- 
jurious.      I'he   upshot   is  that  the   associations   that 
are  the  outcome  of  the  pleasure-pain  response  are  of 
just  the  kind   that   mini.^ter  to   the   animals"   needs. 
Beneficent  arrangement!     Apparently  we  have  to  do 


'.^2 


Sill, In  <    ri   .liiiiinil    /{(Ihiimr 


with  ;i  v(.ii.Tti\  c  a.m'uy  wliiJi  p!csiT\  cs  .iiul  iiitciisi- 
lu's  luM.im  kiiuls  (j|  luh:i\i()r  ami  riiiLts  ntliLTS  on 
tlic  basis  (.|  t!n.-ir  i\-Mi!t^  a  kir,  |  (,\  "siirtiii^r  liciiion" 
in  llir  i\aliii  (it  I'rliav  iiir.  What  louKI  1h-  iiiorc  tclc- 
nlo^iral  I 

I  iic  tact  that  uliat  is  plcasaiir  is  usually  hciicticial 
and  wliat  ;s  paiiitui  is  iisualK  iiiiui-i(uis  may  he  l-\- 
phiincJ  witli  sDiin-  |>hiiisihiiit\-  as  the  result  of  nat- 
ural solution,  as  was  first  (.'inteiuKii  h\  1  lei-hcrt 
Spci.tei-.  \iiinials  uiiiJi  took  pleasure  in  iloiii^ 
lhi:iL;>  \Kh],\\  u  ( n  had  lor  tln-n  and  which  cxpcri- 
cnced  pain  in  doin^  tlnnj-s  w  hi  Ji  w  m.-  i^ood  I'or  thcni 
^^'•iil'l  !h'  \i.-iv  apt  to  tare  dl  in  the  struL,^i,de  t'or 
'\istetiie.  Natural  >-(  leetion  would  e\er  tend  to 
hrin;,  ahout  a  eonditi'Mi  in  uhiJi  the  pleasant  means 
the  or;^Mm.all\  nood  and  th.e  paiiit'ul  means  the  re- 
\erse.  We  should  not  e\[)e(.t  the  u)|-respondenee, 
it  hi-ou^ht  ah(.ut  in  this  ua\,  to  he  complete,  and  it 
"s  rather  in  la\or  ,,|  the  iluorv  that  we  do  not  tnul 
It    so. 

I>ut  Lii-antinii;  this  contention  ,,t'  Spencer,  there  is 
the  miportanr  (juestion  siill  let't  unanswered,  namely. 
\\  h\  do  animals  jollou  wh.it  is  pleasant  atid  a\()id 
what  is  palnlUlr  In  other  uord..  uh\  does  pleas- 
ure remtorce  and  uh\  docs  pain  inhihit?  Mere  is 
another  fundament.il  prolilem  ,ind  ue  find  that  Spen- 
cer with  Ins  uMial  .i|)preciation  (.t'  t'undamental  prob- 
lems was  on  the  -ground  carK  with  a  theor\-.  I'leas- 
ure,  actordmu;  to  Spencer,  is  the  eoiicomititnt  of"  a 
huulit. ned  nervous  dis-har^e;  pain  the  loncomitant 


Tin    ll,<i.iiii.}uj^    <'l    hihlli.j.ih,- 


hri:  ;s  pkuMirc  causes   an  intlu\  ..t    mltsous  uKr^iV 
t,,  i;r'  centers  c<.i;.crnol  \:\  the  iiuncincnt;  the  lines 
,.]■  aisehar^a'  beeonic   "uwvc  permeable,"   and  upon 
repetition  ..f  the  eciulitions  tlie  same  aet   tollows 
uitli   greater   readiness   than   hefuie.      1 1    the    aet   is 
t,, 11. .wed   In-  pain  with  its  concomitant  of  lessened 
nei-v(.us  disehari,^',  the  diminution  of  nervous  eneruy 
serxes  to  prevent  tile  performaiu e  ot  the  aet  m  -e- 
sp.piise  to  the  same  conditions.      Cl..sely  similar  ex- 
planations of  the  physiolo^ry  „i  the  pleasure-pain  re- 
punse  have  been  ^iven  by  Bain  and  b,   Haldwin,  the 
1  itter  declaring'  that  -'plfasure  and  pain  can  be  a^uMits 
ui  accommodation  and  dc\  elopment  onlv  it  the  one, 
pleasure,  can  y  with  it  the  plieiiomenon  '.f  motor  ex- 
cess—and   the    other,    pain,    the    re\  erse—prob  bly 
sdiiie  form  ol   ir.hibition  or  of  antagonistic  eonv       - 

tion."" 

I  he  phvsioln^rical  u.ncomitants  of  pleasure  and 
pain  ha\e  attorded  a  subject  for  numerous  labo'  - 
tnrv  studies  and  almost  no  end  of  theories.  It  has 
been  impossible  duis  far  to  discover  that  either  of 
these  states  is  iinariably  accompanied  by  any  d.eti- 
ical   condition,      d  he  theor\    ot    Spen- 

for  the 


iiite   ph\siolo^u 

cer   and    P«ain    is  open   to  obvious  cnticism, 

man  who  steps  on  a  tack  undoubtedlv  has  a  "liei^ht- 

ened   nervous   disJiar.LTe,"    a^    muJi    as    a    man   who 

shouts  for  jov.      \nd   1  believe   1   am   safe  in  savimr 

that   no   theory   of  the   phvsiolo^^a   of   pleasure   and 

pain  is  i'U  a  .utrulendv   !iiin  basi,  to  warrant  its  be- 


KU 


Siiiilii-^    in     hiiniiil    firlhiiiar 


n)^   i\<^.\n]iA   as   aiuihiiiu;  iikul-   than   a  y  tcfita- 

ti\  (.•  uorkin^r  Inpnth-sis. 

With  oiii  present  kiiowlcni^rc  of  the  psveho-physi- 
nJK^ry  ol  pleasure  and  pai-i,  the  attempt  to  explain 
how  these  states  or  their  physiological  coneoniitants, 
whatever  they  may  he.  can  act  as  ajrents  of  rein- 
forcement ami  inhibition  seems  rather  a  fruitless 
one.  1  he  process  whi^h  we  meet  at  the  be^rinning 
t)t  intelligence  in  simple  asscniatixe  memory  may 
be  formulated  as  follows: 

stimulus — reaction  —pleasure — reinforcement 

physiological  state  .v 
stimulus — reaction — pain — inhibition 


(physiological  state  v 


Spencer,  IJain  and  others  ha\e  entleavoied  to  show 
how  tile  organic  accompaniments  of  pleasure  anil 
pain  motlity  the  creatures'  subscijucnt  responses. 
i5ut  as  the  problem  was  interpreted  by  these  writers 
our  ignorance  concerning  the  physiological  states  .v 
and  y  brings  us  to  a  standstill. 

In  !iis  valuable  work  on  Mia  J  in  Ivmlnlinti 
1  lobhouse  has  presented  a  new  point  of  view  in 
considering  this  problem,  which  has  the  advantage 
of  not  involving  any  general  theory  of  the  physi- 
ologv  of  pleasure  and  pain.  It  is  essentially  a  the- 
ory ot  how  behavior  comes  to  be  adaptively  modi- 
IuhI  through  the  formation  of  associations,     ft  makes 


Tlir   Brq'nunutjs    of   ItitiU'uji'tur 


1.15 


no  atrcni!  r  to  explain  win  iilcasiirc  is  associatcil 
uith  certain  (.•xpcrienccs  anti  pain  with  others.  Such 
association  may  turn  out  to  he  as  incxphcahlc  as 
tlie  problem  why  stimulation  of  the  optic  nerve  ^'ives 
rise  to  a  sensation  of  light  instead  of  some  other 
kind  of  feeling.  What  it  is  feasible  to  attempt  to 
explain  is  why  certain  responses  tend  to  he  repeated 
and  others  tend  to  he  inhibited.  And  this  can  be 
ixplaineil  with  some  plausibility  as  ilue  to  the  con- 
fruity  or  incongruity  of  the  reactions  which  come 
to  be  associated.  I'or  the  sake  of  illustration  let 
us  consider  again  the  chick  which  pecks  at  a  nasty 
caterpillar.  The  irritation  set  up  by  the  caterpillar 
in  the  chick's  mouth  evokes  movements  of  with- 
drawal and  ejection.  The  two  responses  of  peck- 
ing and  ejection  become  associateil,  but  as  the  two 
movements  are  contradictory  the  result  is  inhibition, 
ihe  pecking  reaction  no  longer  occurs  in  the  pres- 
ence of  a  secontl  nasty  caterpillar,  not  because  of 
anv  stamping-out  influence  of  the  physiological  con- 
comitant of  |iain,  but  because  it  becomes  joineil  with 
xn   antagonistic  reaction. 

In  a  previous  paper  by  the  writer  the  attempt 
was  made  to  extend  the  theory  of  Hobhouse  to 
account  for  the  reinforcement  commonly  held  to  be 
caused  h\  pleasure.  The  -assumption  was  made 
that  this  process  is  due  to  an  organic  congruity  of 
the  reactions.  if  the  caterpillar  pecked  at  is  a 
sa\orv  one  there  is  set  up  the  rcHex  of  swallowing, 
i'ecking  and  swallowing  forin  the  normal  elements 


^v> 


Siiiili<^    ill   .hiiiHiil    Ihliiiiinr 


(if  a  eliaiii  rcllcx;  when  one  part  ot  the  structure 
CdtKtriK'ii  is  lAiitcil  it  tcinis  to  increase  the  tonus 
lit  the  associated  parts,  an*!  thus  reintoree  the  orijjji- 
nal  response.  I  ha\  <■  tounil  that  iti  the  crayfish  stim- 
uhition  ot  the  ant(.!"'.iles,  which  are  important  or- 
j^ans  ol  smell,  sets  up  chewing  rno\ements  ot  the 
mouth  parts  and  ^raspu^^  niosements  ol  the  small 
chela-.  Siinilarlv  stimulatinu;  the  ^n'all  chela'  evokes 
cheuiiii^  rno\enients  ot  tlie  inmith  parts  atul  twitch- 
ing of  the  antennules,  wliile  stimulatimr  the  mouth 
parts  (hrectly  inav  cause  movements  in  hoth  the 
other  sets  ot  vir^ans.  \\"e  have  here  as  a  matter 
ot  fact  a  numher  o!  reflexes  which  mutually  rein- 
force one  another.  Suppose  that  in  the  chick  the 
sij^lit-|ieckin^  response  atul  the  taste-swallowing  re- 
s[ionse  are  related  as  the  feeding  reflexes  demon- 
strahlv  are  in  the  cravtish;  the  seconii  response  would 
thus  teiul  to  reinforce  the  tirsf,  and  if  this  tendency 
persisted  v\  e  woukl  have  a  uise  of  learning  by  ex- 
perience. 

Animals  in  the  course  ot  tlu  ir  instinctive  responses 
encounter  stimuli  which  hrinj^  about  other  responses. 
These  become  associated.  .According  to  the  nature 
of  the  nervous  pathways  invdlved,  there  may  he  re- 
intorccmcMt  ol,  or  interference  witli  the  original  re- 
action. I''xper!ence  firings  about  an  extension  of  the 
range  ot  adaptations  by  the  assimilation  ot  con- 
gruent reactions  and  the  elimination  of  acts  whose 
secomlary  consetjuences  are  in  the  nature  of  an- 
tagonistic  and   thereby   inhibitory   responses.      Such 


References 


M 


wc  may  say.  by  way  of  cxprcssiiiij  a  tuitati\c  \  icu- 
pdinr.   is  the  nature  of  priinitixc   iiitcUi^'cncc. 

Hut  it  will  he  seen  that  the  eapaLity  to  torin 
new  adaptations  rests  upon  the  primary  ailapti\e- 
ness  ot  the  instinctive  reactions.  The  power  ot  tor- 
rnation  of  associations  alone  would  never  lead  to 
impro\emcnt.  I'he  adapti\eness  of  '.ntelii^^ence  is 
liaseil  upon  the  adapti\eness  of  instinct:  it  may  he 
said  that  intelligence  is  a  means  of  enahlin^  an  ani- 
mal to  li\e  its  life  more  completely  ami  success- 
fully, hut  instinct  furnishes  the  fumlamental  sprinj^s 
of  action.  I'\en  complex  creatures  like  ourscKes 
jCrm  no  exception  to  this  rule. 


Kii  i:rfnci-s 


Hmn,  .\.  The  senses  and  the  inlellcct.  y\  ed., 
ih(;4.      The   emotions   anil  the  will.   4th   ed.,    iS^t;. 

B.M.DW  IN.  J.  M.  Mental  de\elo[)ment.  Meth- 
ods and  processes.  2nd  cd.  N.  ^  .,  i<>".V  J^^"- 
\  elopment    and    evolution.      N.    V.    i<>'i2. 

HollN,  (I.  I. a  naissance  de  rintelligence  Paris, 
1909. 

Holilluisi.,  [..  \.  .Mind  .11  evolution.  I.omlon, 
ifyo  I . 

lloi.Mi.s.  S.  J.  (  I  )  IMeasnre,  pain  and  the  he- 
irinnin^s  of  intelli^a-nce.  Jour.  Com[).  Veur.  I'sych. 
2u,  145,  i<;i<i.  (2)  The  evolution  ot  animal  intelli- 
gence.    N.  v.,   1911. 


138 


S Indite   ill   .liiiindl   B(litiiiiii 


Jl..\NIN(;s,  II.  S.  (  I  )  Contributions  to  tlic  study 
of  the  bcha\  ior  of  lower  organisms.  Carnegie 
Inst.  Pubs.,  i'>'i4.  (2)  MoJiliability  in  bcha\ior. 
I,  Bcha\ior  of  sea  anemones.  Jour.  I'.xp.  Zool.  2, 
447,  190^.  (3)  Behavior  of  lower  or^anisnis.  \. 
v.,  1906. 

Sri. NCI. K,  II.  IVineiple.s  of  psychology.  \.  Y., 
1892. 

W.XSMWN,  I''.,  instinct  and  intelligen^-e  in  the 
animal  kingdom.     St.   Louis,   1903. 

Wmum.a.n,  C.  O.  .\nimal  behavior.  Biol.  Lec- 
tures, Marine  Biol.  Lab.,  Woods  Hole,    189S. 


VII 

S(»M1.    lONMI^I  KAIIONS    ON     1111.    I'KOBLKM    Ul- 
1.1   \KMSC; 


1^1  il'.  ..■sscntial  nature  of  the  process  of  Icariiinjr 
constitutes  a  proMem  of  such  fundamental  im- 
portance for  psycholo^'v.  to  say  nothing  of  physi- 
oloiry  also,  that  any  iliscussion  which  promises  to 
contribute  anythin^r,  however  little,  toward  its  sol  i- 
tlon  is  abundantly  justified.  In  the  previous  chapter 
an  interpretation  of  the  process  of  learning  was 
hrieHy  outlined,  and  it  may  be  profitable  to  con- 
sider here  some  other  proposed  solutions  of  the 
same  problem,  as  well  as  certain  criticisms  of  the 
view  set  forth  in  the  preceding  pages.  The  formu- 
lation and  criticism  of  different  hypotheses  regard- 
ing the  mechanism  of  learning  is  especially  desir- 
able, since  the  pathway  ahead  is  none  too  clear,  and 
since  we  have  to  rely  to  a  large  extent  upon  the 
method  ot  rial  and  error  in  order  to  make  prog- 
ress. 

An  ingenious  explanation  of  the  learning  process 
has  been  put  forward  by  Thorndike,'  who,  like 
Spencer  and  Bain,  finds  the  explanation  of  the  re- 
inforcement and   inhibition  of   reactions   in  the  pc- 

'  ■Aiiiiiuil   liu<.!liKCin.(.-."      llic  Macmillaii  Lo.,  N.  V.,  lyii. 


I  »'> 


Si/i,Iir\    ill    .Iniiihil    Hilhiii'ir 


uili.ir  |<h\ siold^ii ;il  [>r()i'css(.-s  Mi(i|iosiii  t<>  ammi- 
I'.uiv  flic  satisfying  aiiJ  anno.ln^  ixpcriciucs  of  the 
animal.  I  liormliki.'  rcto^ni/cs  that  uhilo  the  tcii- 
litruA  (if  animals  to  repiMt  rispimscs  that  hrin^  sat- 
islacticn  or  [)lcasuri.'  and  tn  liisKintiiUK'  responses 
that  entail  pain  usually  leads  to  ad\  anta^^eous  re- 
sults, this  lule  is  nut  without  its  e\ecptions.  "Manv 
animals  are  satislicd  h\  tkleterious  conditions.  I'\- 
eitement.  overeating,  aleoholie  intoxication  are,  for 
instarue,  \er\  potent  s.itislicrs  of  man."  anil  i.ondi- 
tions  whieh  are  \er\  salutarv  often  fail  to  proiluee 
satisfaction,  and  m.iv  e\  en  hiin^  positive  displeas- 
ure. \11  this  is  simpK  a  matter  of  imperfect  ail- 
iustment.  "I'pon  examination,"  sa\s  riiorrulike.  "it 
appears  that  the  pernitious  states  which  at)  animal 
welcomes  art'  not  pernicious  at  llit-  limr.  In  llir  ikii- 
rii>ir<.  We  learn  many  had  habits,  such  as  mor- 
phinism. Incause  there  is  incomplete  adaptation  of 
all  the  interests  of  the  hodv-state  to  the  tempor.srv 
interest  ot  its  ruling  class,  the  neurotics.  So  also 
the  unsatistyinu;  ^oods  .ire  not  ^ooils  to  the  neu- 
rones at  the  titiie.  We  neglect  many  henclits  be- 
cause the  neurones  choose  their  immediate  atl\  an- 
ta^e.  I  he  neurones  must  be  trickcil  into  pertiiittinijj 
the  animal  to  t.ike  exercise  when  free/ing  or  i]ui- 
nine  when  in  a  tever.  or  to  free  the  stomach  from 
certain  poisons. 

"Satisfaction  and  discomfort,  wclcominj^  and 
a\-oiding,  thus  seem  to  be  related  to  the  mainte- 
naiue  ;uul  hiiuirance  of  the  life  [processes  of  the  neu- 


(:u)i^i,l.ruli'i>ty    ini   ill,-   riuhlrin    nf   I  ,iirni>i,f       141 

r.-ncs  r:itluT  than  ut   iIk-  animal  as  a  uholc,  an.!  to 
tanporarv  ratlur  than  lurmaiuiU  maintcnaiuc  an.l 

iiimlraiKC." 

\.)\v     the     inoJitiiation     ot     lu'havior     through 
ihaii^^cs    in    the    m-uroiics   is   i.(.nccrn(.»i    chictly    with 
what    aHccts    the    |Krnu'ahility    <)l'    lutain    lines    ot 
comnuinieation    in    the    nervmis    system.       I  he    seat 
(.f  these  ehan^'e's  in  permeahility  is  th<ul^^ht  hy  many 
physiolo^nsts  to  reside  in  the  synapses  or  membrane- 
between  the  ends  of  anastoniosin^r  processes  of   the 
ner\e   eells.      While   the   experimental    evidence    tor 
this   conclusion   is   rather  mea^'^'r   we   may   ad..pt    it 
pr.uisionallv    as    perhaps    the    most    plausible    vuu 
.It   the  present  time.       I'he  condition   which  permits 
the  ready  transfer  i^i  impulses  from  one  neurone  to 
another    Thorndilie  calls  the   "intimacy  of  the   syn- 
apse." and  he  formulates  the  following  provisional 
hypothesis   to  account   for  the  process  of  Icarnm^': 
'•  \    neurone    modifies   the   intimacy   of    its   synapses 
M)  as  to  keep  intimate  those  hy  whose  intimacy  its 
other  life  processes  are  favored  and  to  weaken  the 
intimacy  of   those    whereby  its  other  life    processes 
are  hindered,   'i'he  animal's  action-system  as  a  whole 
conse(]uently    does    nothing   to    avoid    that    response 
whereby   the    life    processes    of   the   neurones    other 
than  connection  chanf^int^  are  maintained,  but  does 
cease  those  responses  whereby  such  life  processes  of 
the  neurones  arc  hintlored. 

'■'I'his  hypothesis  has  two  important  consei]uences. 
Kirst:     Learning  by  the  law  of  effect  is  then  more 


142 


.S //((//(>    ;;/    .tii'nuiil    liilhiiint 


fully  .iii.i|iti\  I-  tor  the  ncurdru's  in  the  ih.in^in^i;  in- 
tiriKuv  lit  uhiisc  s\ iiapMs  k-.irtim^  consists,  than 
titr  the  animal  as  a  uhulc.  It  is  aJaptiNe  tor  the 
animal  as  a  whuje  onlv  in  so  tar  as  his  or^jani/a- 
tion  makes  the  neurones  eoneerned  in  the  learning 
ueleonie  states  ot  attairs  that  are  favorable  to  his 
life  and  that  of  his  species  aiul  reject  those  that 
are  hanntul. 

"Second:  A  iiuchani-^m  in  the  neurones  ^i\es 
results  in  the  behavior  of  the  animal  a-  a  whole  that 
seem  bevond  meihanism.  M\  their  unmoditiable 
abandonment  ot  certain  specitu  conditions  and  re- 
tention ol  others,  the  .iiiimal  .is  a  uliole  can  modity 
Its  bihax  lor.  I  luii-  one  rule  ot  uuuluct  causes  in 
him  .1  countless  con\ple\ity  ot  habits.  I  he  learning 
ot   an  animal   is  an   instinct   ot    its  neurones." 

<)t  course  the  .issumption  that  the  neurones  re- 
act s(>  as  to  make  themsehes  more  [K-rmeable  to 
stimuli  th.it  are  beneficial,  and  to  make  themscKes 
less  permeable  to  stimuli  th.it  are  injuriou",  has  no 
liirect  e\ideiuc  in  its  sup|)ort.  It;,  \alue  consists  in 
its  ser\  iceableness  as  an  explanation  ot  learning. 
Hut  notwithstanding  the  tact  that  reactions  on  the 
part  ot  cells  are  very  tre(|uently  tcleoloj^ical  tlie 
hypothesis  is,  I  believe,  not  in  accord  with  what  is 
known  ot  the  physiology  ot  the  nervous  s\stem.  So 
far  as  we  know,  nervous  im|Hilses  are  the  same  in 
character  everywhere.  We  should  expect  that  u[i 
to  a  certain  degree  ot  intensitv,  like  lunctional  stii  i- 
ulation  in  general,  ner\ous  impulses  would  enhance 


Cnusulniilnni^   <>ii  lit,    PfuhliW   nf   I  rurniii.j       \M 

th.   lite  pn.crsscs  ..I  the  iKur.uus.     <  )Mly  wlun  ..mt- 
stimulatcd    uouKl    uc    c\iH.t    tliit    there    uniiUI    he 
.my   ilelctcrious   or   anii<>\ini:   etteUs   which   .ire   sup- 
|-,,sca  t..  reMih  in  the   reaiuti-.n  ot   the  perme.ihility 
,,|'    the    >>yiia()se.       I'lionuhke's    iloetrine    then    niitii- 
r.ilh     leads    to    the    position    that    the    \itally    k"'"^l 
.itui   pleasant   stiiiuilati(»ns  are   those   ot    (.ptunal   or 
siih-optiinal    intensits,    uhile   stimulations   ot    greater 
mtcnsitv    wouKl    produce   elteets   uhuh    are    unpleas- 
ant  aiui  deleterious,   at   least  at  the  time.      Are   the 
laets  sueh   as  the   theory    uouUi   leaii   us   to   evpect  .'' 
Stinuilation    ot'    pain    nerves    produces    sensations 
uhieh    are   ^^eneralK    <lisa^reeah!e   in    all    decrees   ot 
Intensity    whieh    can    he    ap.preii..ted.      Shall    we    say 
then   that    all   stinuilation   of   the    neurones   in\(.lved 
in   responses  to  pain  ;,'i\in^r  stimuli   are  injurious  to 
the   neurones  involved?      it   so.  praetieally  all  tune- 
tional  stimulation  ot   these  neurones  would  he  ilele- 
ferious   to   them.      On   the   other    hand,   eertam   sen- 
s,)rv  systems  mav  he  stimulated  strongly  tor  a  lon^r 
time    without    producing'    results    that    are    unpleas- 
ant.      It    is    far    frotu    [iroven    that    the    sensations 
aroused   hy    stimulatinji   the    nerves    ot    touch,    heat, 
and  certain  of  the  nerves  of  taste  anil  smell  arc  ever 
dlsa^M-eeahle.   however  strongly   the  end  organs  are 
stin)ul.itcd.      It  is  prohahlc  that  most  of  the  unpleas- 
ant  results   alleged   to    follow    from   ov  erstimulatinir 
a    [Kirticular   sense   or^^an   arise    from   the    fact  that 
pain   nerves  liecome   involved   when   the   stimulatin<r 
agent  is  sutticicntly  stronjj;.      This  is  very   prohahlc 


14 


SiKflit'.'.   ill  ./iiiiihil  Bilunior 


ill  tlic  case  i)f  heat;  ami  thorc  is  more  or  less  evi- 
ileiue  for  the  same  eonelusioii  in  rejijard  to  \ery  in- 
tense \isual  anil  ainiit>)ry  stimuli,  although  it  can 
not  he  regardeii  as  entirely  establisheil.  I'.ven  were 
it  proven  that  overstimulation  of  any  sense  organ 
produces  unj^leasant  eHects  (  anil  avoiding  reactions 
as  a  scconilary  result),  the  unpleasantness  may  he 
due  not  so  much  to  tlie  itijurv  to  the  o\erstinui- 
lated  neurones  as  to  the  b.reaking  over  of  the 
stronger  neural   current  into  new  channels. 

Certain  tastes  and  smells  are  tlisagreeable  e\en 
when  thev  can  Itarclv  he  percei\  cil  at  all,  while  others 
are  welcome  at  almost  anv  degree  ot  intensity.  It 
is  \  cry  improhahle  that  t!ie  disagreeable  (]uality  of 
the  former  is  due  to  the  supra-optimal  stii!Uilatior\ 
of  certain  associated  neurones.  It  is  not  so  much 
the  intensity  of  the  eftect  produced  by  the  stinuilus 
that  gives  rise  to  disagreeable  results  antl  inhibitory 
cHccts  as  the  channels  through  which  the  stimuli  en- 
ter the  ncr\()us  system.  Were  Ihorndike's  theory 
correct,  we  shouKl  exjiect  to  tiiui  comparati\  ely  mild 
stimulations  producing,  ijuite  generally,  [)leasural>le 
feelings,  and  strong  stimuli  proiiucing  disagreeable 
teelings.  and,  liirectlv  or  indirectlv.  a\()iding  reac- 
tions. ( )n  the  contrary,  we  t-nd  the  organism  pro- 
vided with  sets  of  rellex  arcs,  each  of  which  tends 
to  be  set  into  operation  liy  its  own  kinii  of  stimu- 
l;>.ing  agent,  and  producing  feelings  of  much  the 
same  i|uality,  howcxer  their  intensitv  may  varv. 

Another    conse(]uence    of     Ihorndike's    theory    is 


Cn)iufirruti"ii>   on  lit,-  Ptahhrn  "j   l.iaiiinuj      145 


that    reactions    to    disagreeable    stimuli    shouUl    lie- 
tome  rciluecd  the  more  often  thiy  oeeiir.     It   a  rc- 
icptor  is  connected  with  neurones  A,   1^  C  ,   and  D 
Involved  in  a  reflex  response  to  a  stimulus  that  pro- 
duces disagreeable  effects  ami  an  avoiding  .-eaction, 
theti  as  the  neurones  are.   ..v  liypntlifsi,  injuriously 
;itfected,    the   intimacy    of   their  synapses   wouKi   be 
weakened  and  the  course  of  the  impulse  through  the 
system  more  or  less  blocked.     The  ilisagreeable  ef- 
fects and  the  vigor  of  the  avoiding  response  would 
tliercforc  tend  to  wear  away  after  successive  repeti- 
tions.     In   general  it  cannot  be  said,    I  think,   that 
this  occurs.     Castor  oil  ought,  after  being  taken  a 
few  times,   to  become  much   less  unpleasant,   but   I 
\ery  much   doubt  if  this   is   a   common   experience. 
People    suffer   pain    from    a    particular    region    for 
\ears  with  little  or  no  diminution  of  intensity-,  and 
tliere  are  some  things  which  up  to  a  certain  point 
may  become  more  disagreeable,  instead  of  less  so, 
the  more  often  they  are  experienced.     Sometimes,  it 
is  true,  things  which  arc  at  first  ilisagreeable  come 
to   Ik  tolerateil  in   time  with  little   discomfort,  but 
tfiis   is   probably   because   the   incoming  stimuli   be- 
come connected  with  other  neurones  than  the  ones 
which  ga\e  the  original  motor  expression.     In  other 
cases   it  may  be  due  to  quite  different  organic  ad- 
justments.     It  is  tloubtful   if  where  the  unpleasant 
stimuli    continue    to    be    rcspfinded    to    through    the 
same  channels,  there  is  in  general   a   weakening  ot 
the  response  or  mitigation  of  its  disagreeable  (jual- 


14^' 


StuJirs   iu   .Iiiitmil   ntliinior 


ity.  According  to  the  theory,  responses  itnohiiiji; 
unpleas.inr  effects  should  come  to  inhiliit  themselves. 
Such  a  result  mi^hl  shield  the  neurones  from  fur- 
ther injurious  stimulation,  hut  it  would  'tiardly  bo 
eoniluci\e  to  the  welfare  rf  the  organism  in  general, 
since  it  should  keep  on  reacting  so  as  to  axoid 
sources  of  injury.  That  th.ere  is  any  general  ten- 
dency for  unpleasant  responses  to  become  reduced 
in  vigor,  apart  from  the  purely  temporary  effects 
of  fatigue  common  to  all  responses,  is  \ery  ques- 
tionable. 

On  the  other  hami,  there  is  probably  no  general 
tendency  for  pleasant  responses  to  become  per- 
formed with  greater  \igor  or  to  be  accompanieil 
by  heightened  satisfaction.  I -earning  to  like  cer- 
tain articles  of  tood  as  well  as  coming  to  (.lislike 
others  is  probably  a  iviatter  of  secondary  associa- 
tion. .\ddiction  to  alcoholic  elrinks  and  other  so- 
called  habit-forming  ilrugs  is  a  phenomenon  rather 
exceptional  in  character,  the  explanation  oi  which 
nceil  not  concern  us  at  present.  Doubtless  second- 
ary associations  are  involved  here  also,  it  is  prob- 
ably not  the  initial  pleasure  which  these  tlrugs  arouse 
that  impresses  the  habit  of  using  them  (the  sub- 
cutaneous injection  of  morphine,  for  instance,  is  the 
re\erse  ol  pieas:int),  but  some  general  physiological 
effect  which  is  pretty  closely  associated  with  their 
injurious  influence  on  the  neurones.  I'ntler  certain 
kinds  of  intoxication  a  person  mav  experience  feel- 
ings of  pleasure  that  go   along   with   cerebral   con- 


Cnus'uhralioHs  ,>)i  ihc  PmhUm  uj  I.raniiiuj      I47 


ilitions  which  \wc  liLcidcdly  uinvhoK'sDinc. 

(  )rilinarily.  pleasant  tastes  aiul  smells  retain  \ery 
luai-ly    then-   original    al^edonie    iiuality.      Wc    may 
bcrome  more  a[)t  to  seek  a  partieiilar  taste  that  we 
have  had  helore,  hut  this  in  no  way  goes  to  show 
that   the   ori^nnal    response   set   up  hy   the   pleasant 
suhstancc  takes  place  more  easily  or  is  attended  with 
t,rreater  pleasure.      Pleasures  often  wear  away,  and 
things   once    afrreeahie   may   come   to   pall   upon   us. 
I  here  is  little  evidence  that  pleasure-j^i\  in^r  stimuli 
In  general  tend  to  reinforce  themselves,  and  where 
reinforcement  occurs  it  is  prohahly  due   to  second- 
ary associations  with  other  reflex  arcs. 

Ihe  effects  of  agreeable  and  disajrrecahle  states 
upon    subsequent    reactions   to   the    stimuli    immedi- 
ately producing  them  are  much  the  same.     Consid- 
ered as   single   responses  both   may  be   fatigued  by 
repetition  and  influenced  similarly  by  general  bodily 
conditions.       The    notable    thing    about    unpleasant 
responses  is  that  they   exercise   their  inhibitor)-   in- 
fluence on  other  reflex  systems.     It  is  chiefly  in  their 
influence  on  other  associated  reflex  arcs  that  the  dif- 
ferent effects  of  agreeable  and  disagreeable  stimuli 
become    manifest.      The    nasty    caterpillar    in    the 
mouth  of  a  chick  may  not  become  less  disagreeable 
when   picked   up   on   subsequent   occasions,   nor  the 
edible  worm  may  not  give  a  more  intense  thrill  of 
atisfaction.  but  the  experience  with  the  nasty  cater- 
pillar tends  to  check  the   pecking  reflex,   while  the 
seizure   of  the  edible  caterpillar  tends  to  reinforce 


148 


Slii(Ii('s   in   .Iniuuil   lii'litninr 


it.  Satis! ying  ami  aiiiiDviii^  states  do  nut  attcct  the 
reactions  by  whiili  these  feelings  are  iinniediately 
aroused,  hut  otiier  reaetions  pertonned  in  close  tem- 
poral relation  to  them. 

I  he  \arious  theories  [uit  torward  to  e\[ilain  the 
learning  [irocess  as  an  effect  of  the  physiological  cor- 
relates of  agreealile  and  disagreeahle  states  arc  all 
open.  I  helie\e.  to  serious  ohjeetion.  Aside  from 
tile  tact  that  no  theory  as  to  what  these  physiologi- 
cal correlates  are  is  on  a  iirm  hasis  there  is  no  one 
standpoint  tliat  gi\es  a  consistent  interpretation  of 
the  process  ot  Icai'ning.  It  is  not  evident  that  the 
correlates  of  all  the  \aried  states  that  are  annoy- 
ing ha\e  any  general  physiological  characteristic 
which  distinguishes  them  from  the  correlates  of 
states  which  are  pleasurable.  And  even  if  they 
have,  it  does  not  follow  that  these  correlates  are  par- 
ticularly concerned  with  the  mechanism  of  associa- 
tion. 

Ihe  view  i;l  learning  sketched  in  the  preceding 
cha|)ter  has  at  least  the  merit  of  avoiding  anv  as- 
sumptions ill  regard  to  the  physiological  concomi- 
tants of  agreeable  and  disagreeable  mental  states. 
I  he  attem|it  was  made  to  show  that,  given  an  cn- 
tlowment  of  instinct  plus  the  ability  to  form  asso- 
ciations, an  animal  may  aci|uire  modes  of  behavior 
which  ada[it  it  to  new  conditions  of  life.  A  re- 
spc  ise  which  results  in  setting  into  action  a  strong 
instinctive  proclivity  is  remtorceti  or  inhibited,  as 
the  case  may  be,  according  to  its  congruify  or  incon- 


Cnt.tdaalinus  m,  llir  Pml'lnii  "f  l.canuiuj      14') 

^luity  with  the  iir(icli\it\   thus  arousiii.     nniinarily 
a  response  A  tlKit  is  eh-sely  fnlhiur.l  hv   an  iiistinc- 
tl\e  re:Kti(.n  B  iii\(.l\iiiLi  the  liberation  .«t   a  eoiisui- 
eral^le    ainoinU    of    iier\()iis    eiierj^y    is    reinforced, 
probaMy  as  a  result  of  the  influence  of  this  energy 
(,!i    tlie    nervous    coniu.tions    simultaneously    exciteil 
hy  the  response  A.      If.  howexer.  the  associated  re- 
action  15  is  ojiposed  to    \,  as  when   an  outreachnifr 
acti(»n   is   followed  by   a   withtlrawin^'   response,   the 
influence  of  B  tends  to  inhibit  the  first  response  A. 
In  both  cases,  A  and  B  tend  to  becoirc  associateil. 
l^ut  the  different  secondary  reactions  tiave  different 
cflects  on  the  primary  response  with  which  they  have 
beconic  joined. 

Thorndikc  '   has  raised  several  objections  to  the 
view  here  discussed,  but  none  of  them,  I  believe,  are 
fatal  or  even  serious.     ".A   secondary   response    K;; 
may  bind  1^,  to  S,   [the  primary  response  to  the  m- 
itial   stimulus],  e\  en  thouji;h  it  is  incongruous  with 
it,  and  disjoin  R,  from  S,  though  it  is  congruous  with 
K,.       Thus   a    cat    in    a    box.    the   door    of   which   is 
opened,  permitting  escape  and  eating  liluHfVir  the 
,,//  snail  lies  herself,  will  soon  come  to  scratch  her- 
self as  s<n)n  as  put  in  the  box,  though  there  is  no 
congruity    between     escape     through     a     door     and 
scratching."     This  objection  is  based  on  a  miscon- 
ception of  the   sense   in   which   the   word  congruity 
was  used  in  the  statement  of  the  theory  criticized. 
Viewed  as  two  external  acts  of  the  cat's  body,  there 

'  •Educational  Psychology,"  1,  iSy,  lyij- 


15') 


SliiiliiS    in   .1  III  III  til    Bilidiior 


is  no  apparciU  con^riiity  iKtuccn  scratchinji  and  ^ct- 
tiiiK  out  aiul  bcin^  t'cd.  Hut  when  these  acts  ha\c 
been  pcrfdrmcd  a  niitnhir  of  tinics  in  close  sc<]ucncc 
uc  cannot  assume  that  they  uil!  not  torm  a  con- 
jfruous  association.  Ihc  in\estij^ations  ot  I'awlow 
ami  his  co-workers  have  ^one  tar  to  show  that  al- 
most anv  two  acts  performed  at  nearly  the  same 
time  may  become  associateti.  The  sali\ary  reflex 
of  a  dojr  niav  be  set  up  throuLjli  ha\injjj  become  as- 
sociated with  sights,  sounds,  stimulation  ot  the  le^s, 
or  even  the  application  of  a  paint ul  electric  stimu- 
lus. I  low  the  second  act  influences  the  first  after 
the  association  has  been  foriiKHl  is  the  important 
consideration,  and  we  need  not  be  surprised  to  find 
that  certain  responses  are  reinforced  by  acts  of 
\ery  diverse  kiiuls. 

"A^ain,"  says  'I'horndike.  "if  a  cat  is  put  into  a 
box,  X,  with  two  alleys  opening  to  the  North  from 
it.  A  and  B,  ami  if  whenever  it  ad\ances  two  feet 
into  alley  .\  it  is  hit  from  behinti  with  a  club  antl 
so  runs  on  out  of  the  Nortli  eml  ot  A.  whereas, 
if  it  advances  two  feet  into  allev  B.  it  is  ^i\en  a  piece 
of  meat  and  hit  gently  from  in  front,  the  cat  will, 
when  put  into  X,  be  less  likely  to  achance  into  A 
and  more  likely  to  atl\  ance  into  H.  Vet  the  res|ionse 
of  advancing  into  A  {produced  the  congruous  sec- 
ondary response  of  advancing  further  in  the  same 
direction,  whereas  the  response  ot  ad\ancin^  into 
B  produced  the  inconji;ruous  retreat  into  X." 

1  think  the  experiment,  howexer,  is  capable  of   a 


Cnn.uhrann,,^  n„  the  PrMm  nf  l.cantuuj      .>i 

aiticrcnt    interpretation.      When    the    cat    .uKano:. 
int..  allev  A.  «cts  a  hlou   tr..n>  behuui  and  ^,nves  the 
.....idin^  reaction,  she   nat.rallv  cnnes  t^o   associate 
,l,is  av.mlin^,  reaction  with  the  si^'ht  ot  that  parfcu- 
l,r    illev       This   on    a    subsequent   occasion    would 
.  ,u-,e  the  eat  to  ^^ive  the  avoiding  reaction  upon  the 
siuht  of  A.  ana  consequently  prevent  Her  tro.n  .n- 
terine  the  scene  of  her  former  nushap.     W  hen  the 
eat  enters  allev  B,  is  ^^iscn  a  piece  ol  n^eat,  and  hit 
.entlv  from  in  front  and  driven  back,  she  is  forced. 
U  is  true,  to  make,  in  one  sense,  an  incontirm.us  re- 
sponse, althou^rh  she  is  not  prevented  thereby  from 
/nterin^^  B  a  second  time.     Thorndike  does  n,.r  en- 
sider  the  essential  element  of  the  situation  accord- 
ing to  the  theory  criticized  as  well  as  acc<)rdm^,r  to 
his  own   view,-namely,   the   reaction  to   the   meat. 
Without  this,  the  act  ..f  driving  the  cat  out  ot  the 
diev  would  probably  have  inhibited  her  further  en- 
trance      The   association    formed  between   entering 
the   allev   and  eating  the   meat  makes  the   entrance 
to  the  allev,  as  it  were,   a  part  of  the  meat-eating 
reaction,  and  the  first  response  is  repeated  through 
having    been    coupled    with    the    discharge    ot    this 
strong  instinctive  propensity.  , 

Those  acts  which  elicit  an  animal  s  natural  in- 
stinctive reactions  are  particularly  prone  t..  become 
associated  with  the  latter,  owing  to  the  greater  dis- 
eharge  of  nervous  energy  which  these  instinctive  re- 
actions involve.  The  acts  which  are  stamped  in  arc 
those  which  are  consistent  with  the  performance  ot 


I  w 


SiiiJii  ''   ill   ./iiiiiml   litliiivhir 


ail  iiistiiuti\c  :Hti\ity  wliiili  tlicy  have  been  the 
means  (if  settinjf  into  operation.  Where  an  instinct 
is  very  reaiiilv  cliseharjfecl,  as  in  the  case  of  the  fooci- 
takinj;  instinct  ot  a  hiin<,ny  aiiiriial,  acts  which  oc- 
casion this  (lischarj^e  reml  to  become  iiuickly  ami 
lirmly  associated. 

We  may  be  justified  In  saying  that  certain  itistiticts, 
such  as  that  of  devouring  food,  ha\e  a  tjuite  gen- 
eral tendency  to  reinforce  acts  which  brinir  stimuli 
that  ti'rm  the  occasion  of  their  liischar^e.  (  )n 
the  .  her  hanil,  injurious  stimuli  may  tend  to  in- 
hil)it  (|uite  j;enerally  other  activities  with  which  they 
lunc  been  associated.  Animals  arc  supplied  with 
an  elaborate  ecjuipment  of  axoiding  reactions  as  a 
part  of  their  congenital  make-up,  and  as  a  result 
of  the  associations  fornied  throuj^h  experience  they 
come  to  shun  the  thinj^'s  by  which  these  avoiding; 
reactions  ha\  e  been  arouseii.  There  is  nothing  a 
priori  improbable  in  the  assumption  that  animals 
may  be  congenitally  eiulowed  with  connections  in 
the  central  nerxous  system  which  would  enable  them 
to  link  up  their  various  trial  movements  in  ways 
which,  on  the  whole,  are  serviceable.  That  such 
connections  shouKl  exist  is  no  more  Improbable  than 
the  occurrence  of  any  other  form  of  adaptive  or- 
ganization. 

Profiting  by  experience  in  an  animal  of  a  prlmi- 
tice  type  of  intelligence  we  may  conceive,  then,  to 
take  place  as  follows:  The  creature  is  endowed 
with  the  capacity  for  responding  to  beneficial  stimuli 


Considerafwus  on  the  Prahlcm  <>f  l.eanuug      1,3 

by   uiT^rrcssivc.   outrcathiMK'   m.-vcinciUs.   and   to   in- 
jurious stimuli  bv  in..vcincnts  of  withdrauaK  rctix-at 
and  avoidance.      All  these  are  matters  ot   pure   in- 
stinct,     (liven    the    po-.ver   of    formmK'   association, 
between   responses,   the   animal  aciiuires  new   habits 
..f  action  by  repeating  those  resp.)nscs  which  arouse 
instinctive    acts   of   a    con^^ruous   kind,    and   by    dis- 
continuing those  responses  which  arouse  instmctue 
acts  of  an  incon^,'ruous  kind.      Modifications  ol   be- 
havior broui,rht  about  in  this  way  would,  in  general, 
crtect  a  closer  and  more  adequate  adjustment  ot  the 
organism  to  the  stimuli  that  act  upon  it.      I  he  asso- 
ciations   formed   would   be    in    the    direction    ot    re- 
fining the  creature's  instincts  and  adapting  them  t.. 
varied  conditions  of  life.     Intelligence  so  developed 
would  be  quite  generally  subservient  to  instinct,  as 
in  fact  we  find  it  to  be,  especially  in  its  more  rudi- 
mentary  stages   of   developiiKnt.       Ihe   new   things 
an  animal  learns  to  do  are  done  because  they  have 
been  assimilated  to  its  instinctive  activities. 

The  interpretation  of  learning  which  we  have 
been  considering  ascribes  an  important  role  to  re- 
inforcement and  inhibition.  The  essential  nature  of 
these  processes,  despite  much  investigation  and 
speculation  on  the  part  of  physiologists,  still  re- 
mains an  enigma.  If  we  thoroughly  understood 
their  nature  and  knew  something  more  of  the 
changes  (whether  in  the  synapses  or  elsewhere)  by 
which  association,  are  established,  wc  >!i<uild  doubt- 
less be  able  to  penetrate  more  deeply  int..  the  mech- 


>54 


Si  Ill/if  ■>   in   .Iniiniil   Ihluninr 


anisiii  III  iiit(.IIim.'iit  htliivior.  I  uoiilil  not  be  uii- 
ilcrstiinil  as  claiming  that  the  piisirit  aieount  of 
the  loariiiti^  process  is  entirely  ailciiuatc.  There 
are  too  many  little  known  elements  in  the  process 
to  warrant  anythitiy  more  than  a  tentative  ailo[)- 
tion  ot  any  one  stanil|)oirit.  IJiit  the  \  icw  det'etuieJ 
ilocs  not  postulate  the  existence  of  any  physiojoj^i- 
cal  processes  beyond  those  known  to  be  commonly 
manifcsteii  in  the  physiolo^\  of  the  nervous  system. 
Xothinjr  is  assumeJ  in  rejfanl  to  the  physiolo^rical 
correlates  ot  Icasure  anil  [lain,  the  teleolo;,ncal  be- 
havior ol  the  neurones,  or  the  nature  of  the  chancres 
on  which  associative  memory  depemls.  It  is  of 
importance,  I  believe,  to  iletermine  how  far  we  can 
explain  intelligent  behavior  without  multi[)lyin^  en- 
tities by  calling  other  factors  to  our  aiil.  At  pres- 
ent it  is  far  from  clear  that  it  is  necessary  to  make 
such   an   appeal. 


VIII 

nil      IMI'IU  AIIONS    (tl      IKIAI.    AM)    LKKOK 

^plli:  t()iKci>t  •)!  trial  ami  error  is  (.nc  that  has 
1   played  a  proininuU  role  in  nHulcrn  writing's  on 
ownparativcly  psvcholo^'V.  and  especially  those  wh-ch 
u.ncern   themselves   with   the   problem   of   how    be- 
[Kivior  eomes  to  be  adaptively  m.-dihed.    1  he  activi- 
ties of  animals  must  obviously  be  so  shaped  as  to 
preserve  the  life  of  the  individual  or  its  race.        o 
•I  certain  extent  successful  acts  may  be  hit  upon  by 
sheer  accident,  but  for  the  most  part  the  purposive 
behavior    of    an    animal    is    due    to    its    congemial 
,nake-up.     According;  to  the  rcHex  theory  of  mstinct, 
which   commands   a   wide    following   at  the   present 
time,  instinctive  activities  are  fatally  determined  by 
structural    mechanisms   which   are    set   ^nMn^r   either 
bv  external  or  internal  stimulati..ns.     in  either  case 
instinct,    even   in   its   most   wonderful    and   cmplcx 
numifestations.  is,  in  essence,  nothing'  but  response 
to  stinuilus.     And  if  we  ask  for  an  explanation  of 
the  teleolo^ical  character  of   the   responses  we   are 
referred  t.)  "inherited  or^rani/.tion"  for  an  answer. 
As  the  machine  is  constructed,  so  will   it  work. 

Whatever   the   merits  or   deniciits   of   the   reflex 

155 


i;^. 


Siihliiy   III     t'liiihil  Bihini'ir 


til  oiv  III  iristiruf,  it  is  ixiiiciit  tliiit  iii.my  kinds  (if 
:i(l;ipf  i\  I'  luliiiNinr  oiiiir  in  wliich  tlu-  stitmiliis  is 
rrs|><>niK  (I  to.  not  h\  ;i  diritt,  .ipinupriatc  ;ur,  Init 
In  vaiii'il  mo\ittirtits  uliiih  .ipparcntlv  lia\i'  little  re- 
lation tit  tlu-  soiiiHc  or  natiiri'  of  tlu'  stitnulatin^j 
amiit.  I  lll^  is  ucl!  illiistrati  il  hy  tlu-  luhavior  of 
tlu-  proto/oan  i'arama-iiurn  uliiih  has  be-cn  so  ex- 
haustively sfiidieil  In  lemiinjfs.  I'araimrciiini,  as  it 
suiitis  through  the  water,  rotates  about  its  lon^  axis 
aiul  deseribes  more  or  less  of  a  s[)iral  path.  When 
it  eneounters  an  objea  or  reeeives  a  smKicn  stimu- 
lus of  anv  sort  it  reverses  the  beat  of  its  cilia,  swims 
baekuard.  turns  to  the  aboral  sitle  ami  then  con- 
tinues on  its  u;iy.  It  matters  little  on  which  side 
I'aranurcium  is  stinuilated;  its  reaction,  which  Jen- 
nings has  called  the  "nuitor  reflex,"  is  practically 
the  same.  Sometimes  the  ;ju>tor  rellex  brings  the 
animal  into  closer  contact  with  the  stinuilatinK  a|j;cnr. 
If  so,  the  reaction  is  rcpeatcil,  ;itul  continucii  so 
loiijj;  as  the  animal  is  stimulated  by  the  unfaxorable 
coiulitions. 

I'aranurcia,  like  many  oth'.'r  simple  orj^anisms, 
form  agjrrcpations  in  refrions  of  dilute  acitls.  '.'"hey 
are  not  drawn  to  these  chemicals  from  a  distance. 
1  ut  it  a  Paraiiid'cium  happi  is  to  swim  into  the 
area  of  dilute  acid  it  passes  throujj;h  to  the  boundary 
between  the  acid  atul  the  surrountling  water  where 
it  ^ivcs  the  motor  rctlex  and  swims  in  another  di- 
rection. If  it  ap:ain  encounters  the  boundary  it 
gives  the  motor  reflex  and  swims  away,  so  it  is  prac- 


Thf  Impluations   of   Trial  and  Error      i  n7 

tically  cauRht  in  a  s..rt  nf  trap.  Other  IViraiimcia 
happcninn  to  enter  the  area  arc  similarly  .au^^ht.  s.. 
that  an  a^i^ret^ation  of  inJiv  uiuals  is  ^radiialh 
tormea.  I  here  is  no  ..rientation  ot  the  I'arania-ua 
to  the  iliHusln«  cheinleal.  'Ihe  acid  does  .lot  attract 
the  animals  in  anv  sense.  1  he  intusorians  sn.iply 
^ive  the  inot..r  rctlex  when  they  swim  from  acul  j 
to  water,  and  as  a  conse.iuence  ..f  this  simple  re- 
action a  collection   -'t    individual   results. 

Jenninj^s   has   shown   that    Paranurcium   responds 
In    the  motor  rcHex  to  ncarlv   all   kinds  of   -tiinuli. 
IVacticallv  its  whole  hehavior  is  based  on  this  trial  . 
■.uu\  error  method.      The  organism  does  not  directly 
avoid  injurious  stimuli.     The  motor  retlex  may  or 
may  not  relieve  it  from  the  stimulating,'  a«ent.     But 
it  keeps  on   repeating;  the   reaction   until   in  time   it 
chances  to  he  brou^dit  away  from  the  injurious  stim- 
ulation.     When   favorable  comiitions  occur,  its  be- 
havior   continues    unchan^red.       Ihe    I'aram.i-cium's 
philosophy   of   life   is   very   simple.      It   consists   in 
merely    fcillowin^r   the    i'auline    injunction:      "I'rove 
all  things;  hold  fast  that  which  is  good." 

'Ihe  same  general  scheme  of  reaction  Jennings 
found  to  be  very  widespread  among  the  lower  or- 
ganisms.  .Xlthough  the  reactions  ai  the  organisms 
may  be  simple  and  stereotyped,  this  scheme  of  re- 
sponse gives  to  the  behavior  of  these  tonus  a  plas- 
ticity and  adapti\eness  that  keep  them  awa\  from 
injurious  stimulations  and  in  comlitions  favorable 
for   their  existence.      Where    there   is   "error."    the 


'58 


Sliiiliis   in   .hi'  ml    I'i  luiiidr 


orj^aiiistii  tries  ajfain,  ami  keeps  on  -.loin^  so  until  it 
attains  ultimate  success. 

"I'rrnr"  ^enerall-.  means  any  act  prejuilicial  to 
organic  welfare.  The  lower  organisms  are  like 
ourselves  in  avoiding  things  which  are  injurious  and 
in  remaining  uniler  lieneticial  conditions,  whether 
or  not  tfiey  are  influenced  thereto  hy  similar  psychic 
states.  Jennings  teels  "comfHlletl  to  postulate 
throughout  the  scries  certaiti  jilivsiological  states  to 
account  for  the  negative  reactions  under  error,  and 
the  positive  reactions  under  success,"  but  the  search 
for  such  states,  as  I  have  elsewhere  attempted  to 
show,  is  probably  a  vain  (juest. 

In  iiehavior  ol  the  trial  and  error  iy}K',  success 
is  attained,  not  liy  a  direct  ailaptive  reaction,  but 
by  checking  or  reversing  all  reactions  except  the 
right  one.  The  final  outcome  of  the  varied  move- 
ments is  adaptation.  The  method  is  rounilabout 
and  expensive,  but  it  is  better  than  nothing.  It  is 
Nature's  way  of  blundering  into  success. 

'I'hc  capacity  to  gain  anything  through  the  methotl 
of  trial  and  error  presu|iposes  that  an  animal's  re- 
'  actions  to  beneficial  stimuli  are  diflierent  from  its 
reactions  to  injurious  ones.  There  is,  is  I  hope 
to  make  clear,  no  way  of  accjuiring  this  capacity 
unless  there  is  a  congenital  basis  of  adaptive  re- 
sponse to  start  with.  We  are  led  to  the  conclusion 
that  the  aila|itivc  character  of  the  inilirect  adjust- 
ments effected  through  the  method  of  trial  and 
error  is,   like  the  adaptiveness  of  liirect  instinctive 


The  hnplitcilious   of   Trial  and  Error      \  >') 

responses,    the   outcome   of   inhe'-iteJ   or^aiii/ation. 
This    conclusion    applies    to    intcHi>;ciit    behavior 
as  well  as  to  the  more  primiti\e   forms  ot    nulircct 
adjustment.       That  the  burnt  child   dreads  the    tire 
depends  upon  the   fact  that  there   is   an   innate    re- 
tlex  tendency  to  jerk  hack  the  hand,  when  it  comes 
in  contact  with   a   hot  object.      We   have  theretore 
a   bit   of  primary   adaptive    responsiveness  to   start 
with.      1-Aperience  links  up  the   si^ht  of  the  object 
with  this  primary  reaction.      Association  /xr  sc  has 
nothing  teleolo^ical   about   it,  but  it  is  a    means  of 
effecting  further  adjustments,  or  rather  perhai)s  of 
applying  to  new  conditions   the   ada[)tive   responses 
already  present.      If  an  organism   were  constituted 
so  as  to  respond  to  all   stimulations  in  a  pertectly 
hit  or   miss   fashion,    without    any    relerence    to   its 
own       clfare,   it  is   not   likely,   e\  en   it    the   creature 
hail  the  power  nf  forming  associations,  that  it  would 
be    able   to   pro,  t   by   experience.      Suppose,    tor   in- 
stance, it  should  react  to  the  sight  of  an  object  by 
an   act  of  seizure.      Suppose  that   contact   with   the 
object,   which    we    will   suppose   in   this   case   to    be 
food,    should    e\()ke    an    axoiding    reaction    instead 
of  the  usual   purposi\  e   mo\  ements.       I  he   sight  ot 
the   object   becoming   associated    with   tiie    a\.»iiling 
reaction   wouKl  cause  an   inhibition   ot   the   tirst   re- 
sponse   by    calling    into    play    an    antagonistic    re- 
action.     If  f<»oil  were  responded  to  by  an  axoiding 
reaction,    the    associations    actjuired    b-     .xpcrience, 
while  they  might  moilify  behavior,  v     uld  not  hcl[) 


1 6 


u 


Stiniii.s   in  .litimdl   Jirluiinir 


the  animal  out  of  its  unfortuiKitc  situation.  Merely 
assfK-iatiiifi  experiences  is  ot  no  particular  \alue. 
There  must  be  some  principle  ot  selective  associa- 
tion if  experience  is  to  be  turned  to  any  account, 
ami  this  principle  is  supplied  by  the  aniinars  stock 
of  conjrenitally  adaptiv  e  reactions.  What  makes  in- 
telligence of  any  value  to  its  possessor  is  its  injrre- 
dient  of  primary  purposive  responsi\eness.  \\  itiv 
out  this  ingredient,  which  is  the  real  controlling 
hanii  in  an  anima'.'s  life,  beha\  ior  would  be  a  mere 
chaos  of  misdirected  activity.  It  is  really  instinct 
that   makes  intelligence   usetul, 

if  the  adaptiveness  of  intelligence  rests  upon  the 
adaptiveness  of  instincts  and  reflexes,  and  if  the 
latter  is  determined  by  inherited  organization,  we 
must  look  to  the  forces  that  have  moulded  organi- 
zation, i.  e.,  the  factors  of  evolution,  tor  the  pri- 
mary source  of  adaptiveness  in  behavior.  Aside 
from  the  very  doubtful  role  of  the  Lamarckian  fac- 
tor, we  have  at  present  no  way  of  explaining  how- 
purposive  organization  can  evolve,  except  through 
the  operation  of  natural  selection,  (iiven  varia- 
tion (which  may  be  ijuite  fortuitous),  struggle  tor 
existence,  and  the  survival  of  the  best  endowed, 
adaptive  organization  will  be  the  outcome.  Natu- 
ral selection  is  itself  a  sort  of  trial  ami  error  process, 
a  method  of  getting  a  successful  product  (JUt  of  vari- 
ability which,  so  far  as  adaptation  is  concerned, 
there  Is  no  reason  to  believe  is  other  than  ot  a  ran- 
dom,  hit  or   miss  character.      Whether   the  princi- 


The  ImpUiahmts   of   Trial  and  Error      1^,1 

plo  of  selection   .vill  ;uc(niiit.  directly  or  indirectly. 
tor  whatever  there  is  of  purposivcness  in  or^^ani/a- 
tion   and   behavior  is   of    course   an   open   .luest.on. 
I5ut  there  is  no  other  factor  which  is  certainly  opera- 
tive in  shapin^r  tjescent  ah.n^  adaptive  lines,  ami  as 
entities  are   not  to  he   multiplied   beyond  necessity, 
it  is.   I   believe,  justifiable   to   adhere  to  the  theory 
of  selection  until  its  inadeijuacy  is  clearly  established. 
The  position  to  which  we  are  led  is  that  the  se- 
airing  of  anv  advantage  throujrh  the  niethcnl  of  trial 
and  error  presupposes  congenital  modes  of  response 
which  are  adapted  to  >ecure  the  welfare  ot   the  in- 
dividual.     The   method   is  n<  t   the   primary   source 
.,f    adaptive    reactions   so    far   as   the   individual   is 
concerned.     It  cannot  be  the  primary  source  of  adap- 
tive  behavior  in  the  evolution  of  the  race.    .\  method 
of   blunderinir   into   success   instead    of    attaining   it  • 
directly,   it  would   be   of  no   service   unless  the   or- 
ganism were  capable  of  t  .rning  to  profit  its  fortu- 
nate trial  movement,      in  order  to  do  this  the  or-  ^ 
ganism   must  be   provided   for  the   situation  by   its 
inherited  endowment. 

Certain  writers  on  genetic  psycholog>-  have  at- 
tempted to  explain  the  beginnings  of  adaptive  re- 
actions on  the  basis  of  individual  experience  alone, 
(iiven  an  organism  which  just  responded  to  stimuli 
in  a  perfectly  random  manner,  they  attempt  to  show 
how  the  environment  would  discipline  it  into  acting 
in  accordance  with  its  own  welfare.  -Aside  from 
those  functions  which  Jensen  has  included  under  the 


I  6 


Slii(lii>    ill   .liiiiinil    Bihdiiiir 


primarv  |nii|>()si\  c  attiilnitcs  ot  life  { priiniire 
/wcikmassi^k^'ir ) ,  and  wliiili  imist  l>c  presupposed 
it  an  (ir^aiiisin  is  to  lie  an  ori^ainsin  at  all,  we  nat- 
inalK  Mippiise  that  iliirin^  the  early  periods  of 
e\oliitIon  tliere  has  been  a  gradual  suhstitution  of 
atiaptixe  tor  non-ailapti\  e  mmles  ol  l)eha\ior.  If 
the  new  atlaptarions  arise  in  and  throuj^jh  experi- 
ence the\  nui>t  he  transmitted  by  inheritance  if  they 
aeeiumilate  to  the  ad\antai;e  of  the  race.  But  aside 
froin  the  ilillieulties  which  heset  tlie  theory  that  such 
acquisitions  are  inherited,  there  is  invoKed  the  fur- 
ther ditlicultv  of  utiderstandin^  how,  in  the  be^in- 
nin^.  adaptations  could  lia\e  been  aciiuireil  at  all. 
10  this  the  1  .aniarckiaii  mit^ht  ot  course  reply  that 
it  is  a  tact  that  ailaptations  tlo  arise  through  in- 
di\idual  experience,  however  we  may  account  for 
them,  ami  that  it  is  not  especially  incumbent  upon 
him,  ijiia  I.amarckian,  to  explain  their  origin.  There 
is  no  gainsaying  the  pertinency  of  the  Lamar Jrcian's 
answer  as  regarils  the  origin  ot  many  purposive 
lorms  of  behavior.  If,  however,  it  can  be  shown 
that  tlu'  ability  to  aci]u'i-e  special  ailaptations  rests 
upon  innate  modes  oi  reacting  to  stimuli,  and  that 
in  so  tar  as  aci;uired  characters  are  adaptive,  their 
origin  presup[ioses  the  existence  ot  congenital  adap- 
tive reactions,  the  I.amarckian  can  no  longer  dodge 
the  responsibility  ot  explaining  how  these  congeni- 
tal reactions  came  to  be  ot  serv  ice  to  the  organism. 
I'niess  the  characters  acciuired  by  experience  were 
useful  their  accumulation  through  inheritance  would 


Till-  [w['lic,ui(nis   o/    Trial  and  Ermr      \<>}, 

,,hvi()usly  be  of  no  \  aluc.  I  .imiar.ki>in  praa'uallv 
rests  upon  the  assutiiptioii  that  an  <.ru;aiiiMn"s  nat- 
ural modes  of  response  arc  teleol.)j,neal.  But  It  i,n\  es 
no  account  of  how  tluy  came  to  In-  so. 

Can   an   organism   that    responds   totallv   without 
regard  to  its  own  welfare,  if  such  an  organism  can 
he  imagined,  ever  he  hammered  int<i  an  .ulapiiveK 
leacting  mechanism  through  the  iiilluen^e  ot  the  en- 
\ir(.ntnent?      Spencer's   and    Hain's   theories   ol    the 
origin    of    adaptive    movements    practi.alK    assume 
that    it    can.      Moth    Spencer's    and    Hain'>    theories 
assume  that  adaptation  is  hrouglit  about  In  a  process 
of  selection  from  among  the  \arli  us  random    utivi- 
ties  performed  by  the  organism,      it  is  the  acciden- 
tally adaptive  mo\  ement  that  comes  to  be  repeated. 
Both  theories  assume  that  the  adaptive   movement 
is  repeated  because  it  brings  pleasure  to  the  organ- 
ism.     Hence  there   must  be   a  correhition    not  onl> 
between  pleasure  and  welfare,  but  between  pleasure 
and  the  tendency  to  repeat  an  action  by  which  pleas- 
ure is  secured.     To  the  (juestion  as  to  how  pleasure 
came  to  be  associated  with  organic  well  being.  Spen- 
cer falls  back  upon  natural  selection  for  an  answer. 
Organisms  in  which  the  jileasurable  coincided  with 
the  organicrdly  beneticial  were  preserved,  while  the 
others  perished,  so  there  gradually  came  to  be  es- 
tablished the  general  relationship  between  the  pleas- 
ant and  the  beneticial  which  we  commonly  tind.     So 
far  as   I   know,   no   other  plausible   account  o>   this 
relationship  has  been  ottered.      Ihe  I  amarckian  ex- 


164 


StiiJifs  in  An'tmul  Bclurcior 


planatiou  ot  the  orijf'in  of  a(Japti\c  movements 
which  Spcntcr  huiihclf  adopts  has  to  work  with  re- 
lationships which,  as  Spencer  himself  admits,  ha\  e 
been  established  by  natural  selection,  it  is  the  con- 
genital make-up  of  the  organism  that  determines 
which  if  its  \arious  random  movements  comes  to  be 
selected.  In  the  absence  of  the  proper  hereditary 
endowment  the  organism  might  make  random  move- 
ments all  its  life  without  securing  any  desirable  re- 
sult. No  one  has  yet  succeetled  in  showing  how  a 
bit  of  undisciplined  protoplasm  is  able  to  acijuire 
any  form  of  adaptive  behavior. 

We  are  brought  to  the  conclusion  that  the  abil- 
ity to  profit  by  experience,  both  in  its  higher  mani- 
festations as  intelligence  and  in  the  simpler  forms 
of  organic  adaptation,  invokes  an  organism 
moulded  into  at  least  partial  conformity  with  its 
environment.  Ihe  activities  that  are  tiescribed  as 
"trials"  afford  increased  opportunities  for  adjust- 
ment, but  the  ability  to  take  advantage  of  success- 
ful trials  rests  upon  the  basis  ot  congenital  endow- 
ment. It  is  inheritance  that  aHords  the  means  by 
which  inheritance  is  improved. 

Ri'i  i:rfnci:s 

B.\IN,  .\.  I  he  senses  and  the  Intellect.  3d  eil., 
1894. 

Hai.dwin,  J.  M.  Mental  development.  Meth- 
ods and  processes.     2nd  ed.     N.  Y.,  1903. 


ZJOTiKjrx:-^.. 


Rcfercticcs  '"5 

|l  NMN(,s.  H.  S.       The  behavior  of  lower  organ- 
isms.    N.  v..   i9'>^'- 

Ir.Nsi.N,  IV    Organischc  '/wcckmassigkcit.     Jena, 


i9"7 


Sl'l.NiiK,  11.      IVinciplcs  of  Psychology. 


N.  v., 


1S02. 


loRKiv,   11.    1^.      I'ho  mcthoti   of  trial   and   the 
tropism  hypothesis.     Science,  \.  S.,  26,  313.  I9'>7- 


1\ 


111   II  \\  liiK      \\l)    IdKM 


'I'^lil  iilca  has  Nclii  intiitlv  cinpliasi/fil  that  in 
-■■  niaiu  laM-s  tlu'  striKtuii.'  dI  an  (ir^aiiism  is,  to 
a  coiisiiKTahk'  (.xtfiit,  the  (.tttct  ot  Its  hchaxior.  \Vc 
ha\i.'.  (it  toursi,  hui^  hicn  tamiliar  with  tlic  fact 
(il  tuiutiniialK  |U()iluccil  moilitications.  hut  it  is 
(inl\  ot  laU'  tliat  hcha\li)r  has  hccn  hroiight  forward 
as  a  factor  of  iniportancc  in  ilc\  cMopmcnt,  rcj^cricra- 
tioii  aiiil  other  moiics  of  form  rc^uhition.  If  the 
way  in  wfiich  an  organism  acts  is  (Icterniineii  by  its 
striKtiirc,  It  rnav  also  he  said  tiiat  its  structure  is 
to  a  certain  ileyree  determined  Iiy  the  way  in  which 
It   acts. 

I  lie  experiments  of  C  hiKI  on  the  regeneration 
of  [>Ianar'.ans.  nemerteans.  and  other  forms  have 
leii  him  to  the  \  iew  that  one  \ery  important  cle- 
ment iletermining  the  way  in  which  a  part  ditieren- 
tiates  is  the  kind  of  mo\  ements  it  is  called  upon 
to  perform  iluring  the  [leriod  ot  its  formation.  :\ 
posterior  cut  end  of  a  planarian,  tor  instance,  de- 
\elops  a  tail  iH'cause  owmu;  to  the  movements  of 
the  animal,  the  rei^jene- .ting  tissue  is  subjected  to 
the  same  impacts  anti  tensions  to  which  the  tail  end 
of   the  entire  animal  i;  normally  subjected.      Ihcsc 

160 


Bthd\'i<>t    (111(1   Form 


167 


.,,i,ltics  -nnprcs^ca  up-n  the  r.^^cncrat.nji  part  arc 
r.^-arclca  as  the  aircctlve  agents  i.i  tlu'  process  ot  dit- 
Urcntiat-K.n,  ami  it  the  annnal  were  f.  act  m  a  very 
.ilH.rent  manner  .luite  ditlerent  torniatne  processes 

wuuKi  result. 

ChiUi    l..una   thai   In   pieces   of    I.eptoplana   which 
,,..re  caused  to  creei^  m  a  circular  course  owm^  to 
unilateral    injurv    of   the    anterior   en.i   the   new   ta.l 
,|,,,t  was  forn.e.i.  instead  <.f  K'n.wini,r  out  posteriorly. 
.Kveh.ped  in  an  oMiMue  position  in  accordance  with 
,l,c  altered  activity.     'The  regenerating  part  «n.ws 
in  the  direction  ..f  the  principal  tension,  even  though 
,his  formsanan^leof  -r.     with  the  principal  direc- 
tion of  growth."     In  speakinjr  „f  the  ..rd.nary  activi- 
ties of  Leptoplana,  Child  says:     "It  can  scarcely  be 
.louhted  that  these  movements  play  a  part  in  shap- 
in^r  the  regions  in  which  they  occur.     A  cmpanson 
between  fre.iuency.  amplitude,  and  torce  ot   the  un- 
.lnh,tin^   movements   and   the   decree   ot    lateral   de- 
velopment in  the  re^nons  in  which  they  occur  is  most 
strikin^r.      \ccordina  t-.  the  usual  p.)int  ot  view,  this 
correlation  between  structure  and  functH.n  is  merely 
one   of   the  manv   remarkable   cases  of   adaptation, 
hut  in  my  opinion  it  is.   at  least  in  part,  the  direct 
result  of   function   in   the  Indi\idual.    .    .    • 

"  \s  rejrards  the  manner  in  whi.h  the  movement 
„uiv  atlect  the  tissues  it  is  not  difficult  to  see  that 
the'  movement  of  these  parts  to  and  t  ro  through 
the  uatcr  must  subiect  them  to  tension  in  the  lat- 
eral direction.      This  must  attect  in  greater  or  less 


ir.s 


Siinliis   in   ./ii'miiil   lichaiior 


(lt•^;^c■c  till'  ilistrilmtion  ami  ananycmcnt  of  the  plas- 
tic tissin's  tompdsiiijr  the  parts.  \  very  simple  phys- 
ieal  experiment  ser\e>  to  ilhistrate  this  point.  A 
eyh'mlrical  or  s(|uare  stiilv  of  seaHiiij;  wax  mosed  to 
ami  fro  in  water  sufficiently  warm  to  soften  it  will 
umlerfjo  liattcninjr  in  a  plane  at  ri^ht  an^'les  to  the 
Jirection  of  movement.  The  ehan^'e  in  form  is  more 
strikingly  shown  if  a  ri^'ii!  axis  is  present;  a  mass 
ot  wax  moldeil  in  eyiimlrieal  form  about  a  stiff  wire 
will  become  in  a  few  minutes  a  thin  flat  plate  de- 
ereasinjr  in  thickness  towanls  the  ed^es  and  with 
a  roumletl  outline.  The  riuchanical  conditions  re- 
sultinjr  from  the  mo\  eryient  of  the  wax  throui^h  the 
water  are  not  widely  ilitferent  from  those  which  the 
undulatinjr  marjrins  of  I.eptoplana  [iroiluce.  If  the 
wire  axis  of  the  wax  he  considered  as  the  lon^ri- 
tudinal  axis  the  effect  of  movement  through  the 
water  is  lateral  extension.  In  I.eptoplana  the  un- 
ilulatin^r  movement  is  confined  chielly  to  the  lateral 
regions  in  the  anterior  third  of  the  hotly  and  it 
follows  that  the  condition*  tlescribed  are  limitetl 
chiefly    to    these    parts." 

"  I  here  can  be  littb-  iloubt.  in  my  opinion,  that 
these  mechanical  comlitions  constitute  a  factor  in 
the  formation  of  the  broad  lateral  rej^ions  in  I.epto- 
plana and  more  especially  in  other  forms  in  which 
the  undulating  mo\ements  of  t  se  parts  occur.  In 
other  wortis,  the  form  is  in  some  decree  the  result, 
not  the  cause,  of  the  characteristic  methoil  of  ac- 
tivity." 


lh-luriii>r  and  Form 


169 


w 


1„  cxp.n.ncrus  on  IManarM  ChiUl  has  shewn  that 
t'K    lu-;ul   a.ul   phaisnx   do   not   atta.n   thc.r   n..rnuU 
.hapc   ana  struaurc   wl.cn  nu.^cMu:U  is  hirK'cly   m- 
lubitc-a  hv  an.r.thctKs.  but  he  docs  wx  conckulc  that 
nuivcnicnt  is  the  only   tacti.r   involved.      Ketrcnera- 
t,on  and  all  other  ni..  les  of  the  regulation  of  or- 
,Mnic  form  he  regards  as  the  outcome  ol   functional 
regulation.     Mover    nl  plays  a  certain  role  m  shap- 
irur  the  ..utline  of  ^     ne  organisnis,  especially  those 
./„h  physically  plastu  tissue^,  hut  -'it  is  nierely  one 
,,f  a  great  variety  of  functional  factors. 

While   studying   the    regenerati..n   ot    the   infuso- 
,.;  u,   l,oxoph,llum  1   found  that  I  was  dealing  with 
an  organism  in  which  regeneration  and  behavior  are 
apparently    clo^ely    connected.       Loxophyllum    is    a 
llattened   infusorian  that  moves  by   gliding   on  the 
bottom  on  its   right  side.      It  confines  its   activities 
usually  to  a  small  area  for  a  considerable  time;  t.rst 
it   glides    forward   a    short    distance,   then    rever  es 
its   cilia   and   swims   backwards,   turns   toward  the 
oral  side  and  then  swims   forward  again  in    i  new 
direction.     As  the  animal  swims  forward  th     bodv 
is  elongated,  but  as  it  goes  backward  the   body  is 
iiuariably  shortened  and  widened,  thus  showmg  a 
constant   association  between   the   direction   of    the 
beat  of  the   cilia   and  the  contraction   of   the   myo- 
ncmes.     In  the  changes  m  the  form  ol  the  body  it 
is   the   ccmtraction   and   extension   ..f   the   oral    side 
that  play  the  most  imp..rtant  part,  and  it  is  along 
the    oral    side    that    the    inyonemes    are    especially 


Siiiiliiy   III   .hiniiitl   lliliiiiiiif 


abuiulaiit  ami  nl  laij^r  ^i/c.  In  ^mn^  lurwanl  the 
lioiK  hcmis  oralK  aiul  rrcijiufitly  iiiuiulatcs  about 
ill  a  very  \aiial)l(.'  riiaiiiur.  I  lit"  backwanl  ami  for- 
ward riii)\cincnts  of  I  .ovoiiliyUum  may  he  performed 
in  much  the  same  way  tor  a  loii^i;  period  apparently 
without  any  external  stinuilation.  I  he  or^i;anism  is 
capable  of  many  kind-,  of  behavior  under  diHercnt 
ccKiditions,  but  its  usual  activities  are  all  that  con- 
cern  us   in   the   prese?it   connection. 

As  has  been  tound  in  other  infusorians,  the  be- 
havior ol  pieces  info  which  the  oriranism  is  cut  is 
closely  similar  to  that  of  the  entire  individual.  Ihe 
pieces  ot  this  species  regenerate  so  rapidly  as  a  rule 
that  one  can  actually  watch  the  process  K<'''iJ?  <"i- 
An  excellent  opportunity  is  thus  affordcil  for  stuily- 
injj;  whatever  connection  there  may  be  between  the 
activities  of  the  piece  ami  the  changes  of  form  that 
occur  in  it. 

In  the  rejrcnerative  chanjj[es  of  the  posterior  half 
of  the  boily,  for  instance,  we  fuul  that  apparently  as 
a  consccjuencc  of  the  elongations  and  contractions 
that  accompany  the  forward  and  backward  move- 
ments, the  general  form  elon^nites  and  becomes  more 
narrow.  The  cut  end  is  partially  closed  in  by  the 
drawinjj  tojjether  of  the  two  marj^ins,  the  oral  side 
extendinjr  over  rather  more  than  the  aboral  (Fig. 
i).  In  the  movements  of  the  animal  it  may  read- 
ily be  seen  that  the  oral  side  is  pushed  ahead  as  the 
animal  swims  forward  as  if  it  were  making  active 
cftorts   to   stretch   itself   out.      Both   margins,   how- 


liilhiii'ir   iiuil   h'nttn 


171 


.^,1.  t.iko  part  in  this  lutivr  cxtcMsiun.  In.t  tlu-  oral 
snK'  is  tl.c  ninri-  .utivi  Miid  s.m.ii  it  rnav  he  seen 
,,,  push  an.uiul  tlu'  anterior  en.l  of  the  hotly,  and 
it.  invoneines  and  nha  are  thus  hroii^'ht  into  the 
,h;iracteristie  curvature  uhieh  is  found  at  the  an- 
icrw.r  end  of  the  entire  ory;aniMn. 


!i,n«   U,.-",n..'lu:.l  .tr.t'ilm.,  -f  (Ik-  .ili.lr.l  n.ar,,,..     ....  .......11.. 

If  the  cut  is  made  obliquely  {V\g.  2)  so  as  to 
limit  considerahlv  the  extent  of  the  oral  sule.  the 
same  method  of  regeneration  is  followed,  the  <^ral 
^ide  is  gradually  stretched  out  so  as  to  torm  the 
oral   side   and  anterior  end   of  the  new   md.vidual. 

In  the  process  of  regeneration  here  followed  the 


172 


Stiiilii's   in  .hi'nnal   lirhai'mr 


final  fonn  of  the  organism  is  rcathcd  Iiy  the  sim- 
plest and  rjiost  direct  means, — there  is  a  minimal 
amount  o^  formation  of  new  structures.  The  cut 
eml  does  not  differentiate  any  new  org.  ns.  but  the 
old  differentiateil  parts  are  stretched  out  to  form 
the  structures  of  the  new  individual.  It  may  read- 
ily he   seen   that   the   activities  of  the   organism   in 


I'lc.  .'. —  HcmMiir.itiDii  of  I.ii\o|)li\  Mum  .-iflrr  In  iiijr  cut,  .i*-  ^linwii 
l>v  the  two  (lotted  lines.  The  smiill  [larf  of  the  cilhited  Tiiar^in 
Ih.il  reiiiiitis  is  st  ret. ■lied  liiit  .1  short  di^t.lllee,  while  new  cilia 
.ire   foriiied  aloiij;  the  Miw  oral   inartrin. 


extending,  contracting  the  hoily  and  in  constantly 
pushing  the  oral  side  farther  ahead  than  the  altoral, 
tend  to  mould  the  piece  into  the  normal  form  of 
the  species.  In  other  wf)rds  it  might  he  saitl  that 
the  organism  pulls  itself  into  shape.  The  piece 
gets  pulled  into  the  form  of  the  entire  animal  he- 
cause  it  heha\cs  essentially  like  the  entire  animal. 
So  far  the  results  seem  to  support  the  view  that 
form  is  the  result  of  activity,  at  least  to  a  consid- 
erable  degree.      liut   instructive    de\elopmei:ts    are 


Behavior  and  Form 


173 


\uldccl         further  experiments.     By  making  a  cut 
,.,    IS  t  novc  all  the  oral  margin  with  its  dif- 

tcrcntiai  a  structures  we  compel  the  organism  to 
follow  a  luite  different  method  ol  regeneration 
dig  3).  At  first,  owing  to  the  absence  ot  the 
more  Contractile  and  extensile  elements  ol   the  oral 


,.„,   '5_U..p.n.Tation  ..f  I.oxn,,l,yllu.n  aft.r  nMnm:.!  ..f  n.ti..-  oral 

margin. 

side,   the   ahoral  margin  in  the   movements   of   the 
animal  are  pushed  farther  ahead  than  the  ora  .     I  he 
organism     elongates     and     becomes     pushed     oyer 
toward  the  oral  side.     Later,  however,  the  oral  side 
becomes   thinned    out    and    more   transparent;   cilia 
„u.ke    their    appearance    in    scattered    groups     new 
trichocvsts   are    developed,    and   contractile   threads 
appear' in  the  thinned  out  region.     After  these  vari- 
ous  structures   are   developed   the   oral   side   begins 
to  extend  and  ontract  more  than  the  aboral.      1  hen 
it  becomes  pushed  ahead  more  and  more,  and  hnally 


•74 


SliiiJi('.y    ill   J  III  null   liiliiiiior 


is  carricii   aroutiil  the   anterior  ctul  ot    the  liody   as 
in  the  nnrma!  animal. 

In  this  experiment  the  animal  is  toreeti  to  follow 
a  method  ot  regeneration  very  ditterent  trom  that 
pursued  in  the  experiments  iirexiously  deserihed. 
'i'he  oKl  liiHerentiated  parts  are  not  stretehed  out 
to  tOrm  the  neu  ones.  Inn  the  struetLires  ot  the  oral 
sitle  of  the  new  individual  are  lormed  ,/r  ikiid.  it 
is  an  interesting'  t'aet  that  the  tiim  reijuireii  tor 
regeneration  in  th.e  first  ease  is  short,  the  |)roeess 
bcin^  com|ileted  in  a  little  over  an  hoin',  while  in 
the  latter  ease  it  was  not  eompleted  until  about 
fifteen  hours.  In  the  latter  e\[>eriment  tin;  eharac- 
tcristie  behavior  of  the  lu-a!  side  had  to  wait  upon 
the  differentiation  of  the  oral  region  ot  the  body. 
Where  rej^eneration  is  apparently  proilueeil  lari^ely 
bv  the  or^aiism  pullin;^  itself  into  >hape  through 
its  charaeteristie  mo\  ements  behav  ioi'  seemed  to  leail 
the  way  in  mouldin;^  the  normal  form.  In  other  ex- 
periments the  eharaeteristie  movements  IkuI  to  wait 
until  the  finer  differentiations  of  the  organism  were 
(.ic\elo(K"il  bv  other  factors:  tlun  behavior  stepped 
in  to  help  mould  the  alrea^lv  ditfer<iUiated  orj^an- 
ism  into  its  normal  outlme. 

I  think  that  the  tore^oin^  experiments  (  antl  I  have 
ileseribeii  on!\  a  small  part  of  the  number  that  were 
made)  indicate  that  he  more  fundamental  faetois 
in  the  regeneration  o!  this  orj^anism  are  not  so  mueh 
its  gross  activities  as  various  iiUernai  factors  which 
we  need  not   here  attempt  to  specify.      At  the  same 


T   T  T       _-  -._* 


Rcfcrcuccs 


ilS 


time  the  hchavior  of  the  intiisoriaii  is  a  link  in  the 
chain  of  causes  by  which  tlie  tina!  form  is  brought 
about,  but  it  is  concenied  more  in  aeterminin|i  the 
reneral  shape  of  the  body  than  the  liner  lietails  of 
its  internal  structure. 

What  is  true  in  this  case  has.  1  beliexe.  a  rather 
^rcneral    appHeation.       The   gross    general    belia\ior 
of  an  animal  plays,  I  believe,  a  subordinate  though 
.It  times  an  importar.t  role  in  the  determination  ot 
organic  form.      But  when  we  turn  our  attention  to 
the  internal  processes  which  are  responsible  tor  tlie 
finer  details  of  organization  may  we  not   again  en- 
counter problems  ni  beha\ior?      May    n.)t  the   dil- 
ferentiation  of  these  parts  be.  to  a  considerable  de- 
^rree  at  least,  the  result  of  the  behavior  of  their  com- 
ponent  elements?       Ihe    .tudy   of   iliHerentiation   in 
higher  organisms  where  it  is  possible  to  lolluw  the 
activities   of   the   various   cells   which    make   u|)   the 
body  makes  it  e\  ide.it   that  such  is  the  case.      1  he 
imK'  of  this  factor  will  be  considered  in  the  chapter 
(hi    ihe   Beha\  ior  ot    C  ells. 


hi:m:kfnci:s 


Cilii.n,  C.  M.  (i)  Studies  on  regulation.  I\  . 
Some  experimental  n.oditicati.ms  of  form  regula- 
tion in  l.eptoplana.  Jour,  l-.xp.  /ool.  i,  <>>',  1V"4- 
(2)  The  regulatory  change  of  sh.ipe  in  I'lanana 
dorotocephala.      Biol.    Bull.    i6,    277,    i<>.m^.      (3) 


176 


Siudiis   in  Juimttl   lirlitnior 


Analysis   of    form    regulation    with    the    aiil   of   an- 
a-sthetics.     1.  c.   16.  277.    1009. 

IIoiMls,   S.   J.      Behavior  of    I.oxophylluin   and 
its    relation   to    regeneration.      Jour.    l.xp.    /ool.   4, 


I  III,    HIIIAVIOR    OF    Cl.I.I.S 


SI  NCI',    the    cpoch-makinjr    proimilKation    of    the 
cell  theory  bv  Schle'ulen   .md  Schwann  bioloj^ists 
h  ive    comino'nlv'  looked    upon   the    component   cells 
,,1  the  l-odv  more  or  less  in  the  li^ht  ot  little  orjran- 
isins,   each'  with   its   o.n    iiuliviauality,    each   carry- 
P   r  on  the  business  of  its  life  to   a  certam  dej^ree 
independently  of  its  fellows,     llacckel  speaks  of  a 
,cll  soul  which  he  regards  as  a  quasi-discrete  bit  of 
psychic   hfe.      Binet   in   his   /'.y< /»/.     /i/r   "/  Mnru- 
nrc,a>n^m>    writes    of    the    various    psychic    faculties 
inmifested  by  the  white  blood  corpuscles  and  other 
cells  of  our  bodies.     And  Lloyd  Morgan  in  his  book 
,,n    .Innnal   lUhavm,    devotes   a    section    to   the    be- 
havior of   cells  and  shows  how   various   formative 
processes  are  to  .i  considerable  extent  the  outcome 
uf  coordinated  cell  activities. 

The  study  ot  cell  behavior  has  been  ^rrcatly  stim- 
ulited  bv  the  development  ..f  a  branch  of  blolojr,cal 
investigation,  variously  known  as  developmental 
mechanics,  physiology  of  development,  etc.  which 
has  for  its  aim  the  analysis  of  embryonu  develop- 
nicnt,  regeneration,  and  other  formative  activities, 
-  in  a  word,  all  those  processes  which  lead  to  the 

177 


wm 


178 


Siii<li(>   ill  .liiiituil  liiliiiviiit 


prciliK'tion  and  maintenance  of  the  normal  form  of 
the   or;ranism.       The   seietue   of   ile\  elopmental   me- 
ihan'ks  is  of  \erv  rceent  growth.     Its  already  numer- 
ous ile\otees  endeavor  to  ^^ain  a  ileeper  insight  into 
the    nature    of    development    than    it    is    possihle    to 
ohtain  hv  the  older  methods  of  (.icseri|)ti\  e  emhryol- 
o^v  .      However  full  ami  exact  our  knowledge  may 
he  rcf^ardinii  the  tleava^fc  of  the  e^^,  the  formation 
of   the   ^;erm    lavers.    ami   the   ditterentiation   of   or- 
gans;  however   thornu^hlv   we    may   come   to   know 
the  se(iuence  of  events  which  lead  from  the  ejxjj;  cell 
to  the  ailult  atiimal.  such  knowledi^e  does  not  ncces- 
sarilv   reveal  the  threatls   of  causal   connection  that 
govern   the   course   of  develojiment.       I  he   develop- 
ment   of    anv    organism    is    a    wonderfully    complex 
process.      We  mav  descrilie  what   ijoes  on  with  the 
greatest  iitlelity  to  every  iletail,  hut  the  causal  rela- 
tions are  so  involved  that  we  can  seKloiii  discover 
them  without  special  methods  of  analysis.      I  he  sci- 
ence of  developmental   tiiechanics  set  itself   the  task 
not    merelv   o\    descrihinj^   what  takes   place   hut   of 
explaining   why   it   takes   place.      Description   it   re- 
j^ards  as  suhsitliary  to  exjilanation.     Having  for  its 
aim  the    search    for  causes,   it  naturally   ailopts   ex- 
perimentation as  its  chief  method.     Developinj;  c^^s 
are   shaken    apart,    suhjected    to    heat    and    cold,    to 
chemicals    and    a    ^reat    variety    of    other    external 
ajxents:  [^articular  parts  of  the  emhrvo  are  removed, 
ilisplaccil,  or  replacetl  hy  other  parts,  ami  all  sorts 
of  modifications  of  development  are  induced  in  or- 


riir   lidiaii'ir 


,f  (:,■!!.> 


179 


^lc!•  to   discover   sonic 
pciulcncc     subsisting 


tliinii  of   tlu'    relations   ol    Jc- 


bctw 


ecu     tlic     \  a  nous 


activi- 


ties w 


hich  lead  to  the  format 


idii  I 


)t'  the  embryo. 


When  one  \va 


tches  the  early  development  ot  th 


^■m 


)f 


r  ot  a  mo 


Husk 


or  anne 


lid 


worm, 


follows  tl»e  reji- 


lar  and  almost  mathematically  precise  way  1 


.11  division  occurs,   aiK 


1  tht 


n  which 


method  bv   which  the 


ce 


lis  V 


leeome   arrangei 


in   a 


tern 


thi 


en  observes 


tht 


11 


fold 


perfectly    regular   pat- 
nd  overgrowth 


m^rs 


that   lead   to   the   ^astrula    stajre,    and   the    difieren- 
lar  cells  to  form  the  or^r.uis  ol  the 


tiatlon  of  particu 


einnryo, 


he  canno 


t  escape  a  feelin^^  ot   wonder 


that 


l>it  of  simple  materia 


1.  sucii  as  tlu   undivided  e^^ 


ippears   to   lie.    contains 


such   \ 


lowers   o 


and 


well-orclerctl 


construction. 


f    elaborate 
marvellous 


builder  this  bit  of  c^r^  substancj '.  It  is  comparative  y 
easy  to  make  a  sort  oi  roufrh  catalo^,uie  ol  the  meth- 
loys.     Development  may  be  said  to  be  an 


oils  It  employ 
)f 


ittair  of  cell   iHvision,  cell  ^ 


11 


irrow 


th,  cell   differentia- 


tion, 


.hanjres  in  the  form  o 


f  cells,  changes  in  their 


position,   e 
a  iiiere  pre 


sses 


IS 


sis. 


tc. ;   but  this  cataloj^uin^r  o|    proce 
liminarv  to  the  business  of  further  analy- 

t  di 


In  order  to  build  up  an  embr\o.  cells  must  di 


vide,  they  must  in  most  cases  jrrow 


and  thev  must 


uet    into 


the    riM:ht    relative    po 


SI 


tion    and    ditterenti- 


ate,  some  m  this  way  ani 


ta 


blish    a    harmoniously    workini^    Mieehanism. 


d  Nome  in  that,  >o  as  to  es- 

rki 


most  organisms  lorm 


ative   processes  mvDlve  a  ct»ri- 


su 


lerable  amount  of  cell  mov  ement.     Sometimes  this 


IS   passive. 


as    when    cells   are    pu-<he. 


puliei 


1   1 


)V 


I  So 


Sii((lii-.\   in   .Iniiuiil   Hiluiiior 


means  ui  osrncjtic  cliaii^cs  or  growth  processes  occur- 
ring ill  other  parts.  Hut  it  is  corning  to  lie  rcio^iii/ed 
more  antl  more  lli.it  main  ot  tlie  proicsses  ol  eiiihrv- 
onie  tle\  elopmeiit  are  tlie  result  ot  .n.ti\e  cell  mo\e- 
meiit.  .Many  cells  in  e.irlv  ile\  elopment  have  a  con- 
sicierahle  power  ot  locomotion,  aiul.  like  the  soKlicrs 
of  a  uell-ilisciplineJ  armv.  they  move  into  their  ap- 
pointeil  places  at  the  proper  time.  I  o  ii,.\'\n  an  in- 
sight into  this  feature  ot  their  development,  to  un- 
ilcrstand  why  it  is  that  these  cells  act  a-,  they  do. 
we  are  natur.illy  led  to  a  stuiiy  of  cell  hchaviur. 
I'o  a  consiilerable  extent  the  form  ot  our  bodies  is 
an  expressitMi  of  shall  we  say  cell  psychology.''  Or, 
at  any  rate,  it  is  in  part  the  expression  of  that  kinil 
of  bcha\ior  which  is  embraced  under  comparative 
}>sychology  when  found  among  lower  organisms. 

.\  few  years  ago  Wilhelm  l\oux,  an  investigator 
of  especial  prominence  among  the  experimental  cm- 
bryologists,  fouiui  that  if  the  cells  ot  the  trog's 
egg  are  shaken  apart  during  early  stages  of  seg- 
mentation, ami  ()laccd  in  w.iter  a  short  distance  apart 
they  would  slowly  approach  one  another  until  they 
came  into  contact.  This  peculiar  behavior,  which 
was  later  observed  also  by  Khumbler,  was  called 
by  Koux  C'ytotropism.  Whether  it  is  a  torm  of 
cheinotaxis,  or  just  how  it  is  brcnight  about  is  un- 
certain. Cells  of  the  early  cleavage  stages  also  show 
a  marked  teiulency  to  come  into  contact  with  one  an- 
other as  closely  as  possible.  While  they  round  up 
iluring  ilivision,   during  the  resting  stages  the  cells 


Thr    lirluivinr  of   Cclh 


l8l 


It  tii^ctluT  SO  a-^  to  ka\c   no   s| 


.ux-s  lictwi'cn  the 


m. 


his  trait  in 


,t  oiiK  wwU  to  kill'  the  iflls  lit  a  c 


(Hll- 


M.ut  mass.  l>ut   it   has  other  important    fiiniti(.ns  as 
V  .    shall    sec   hitir  on. 

I'hc   tells  of    the   emhryonie  tissue   lalled    mesen- 
JiMue  have  lont:  been  noteil  for  their  powers  of  mi- 
gration.      These     eells    are     usually    irregular    and 
Jian^rcahle  in  outline,   and   are   able  to  ercep   about 
■nueh   like    an    Amu'ba.      Tsually  thev    form   iTiasses 
IvinK'    between    other    cell    layers.      Their    ou^xn    is 
varied,  and  thev  frequently  move  to  a  eonsulerable 
,listancc   from   their   source.      .\n   excellent  illustra- 
ti,,n  of  their  behavior  is  affonlcil  In  the  early  de- 
velopment of  the  sea  urchin.     In  the  region  of  the 
hollow  blastula   which   is  bein^'  pushed  in  to    form 
the  primitive  ^astrula  cavity  there  is  fiiven  off  mto 
the-    interior  of   the   embryo   a    number   ..f   ama-boid 
alls.     These  wander  away  from  their  point  of  or- 
i.rin  and  take  up  p-.sitions  on  opposite  sides  of  the 
M-ehentcron.   where   thev   form   two   groups.      Why 
An   the  mesenchyme  celis  take  up  their  position   in 
these  particular  places?     Driesch  found  that  by  vig- 
orously shaking  the  young  embrvos  the  mesenchyme 
cells   became   loosened    and   scattered   about   irregu- 
lars in  the  cleavage  cavity.     After  the  embrv'os  had 
tnen  left  for  some  time,  however,  it  was  found  that 
these  mesenchyme  cells  \vere  back  again  in  their  nor- 
mal  position   as   if   they  knew   what   was   their   ap- 
pointed  function  and  took  up  their  station  accord- 
ingly.    We  may  conjecture  that  it  was  some  chemo- 


IS2 


StiiJir^    ill    ./niiihil   liilidiinr 


t;utic  influence  that  drew  these  cells  to  certain  re- 
gions <'t  the  iriibrvo  uuicli  as  white  hhnni  corpuscles 
arr  attracted  to  siilistatues  proiiuced  by  certain  bac- 
teria; or  possihh  it  mav  have  been  some  form  of 
uactiot)  to  tdtitact  stimuli:  but,  ariyway.  the  result  is 
of  interest  in  showing  the  role  played  by  cell  mijj;ra- 
tion  in  establishing  the  structure  ot  the  embryo. 

The  meseiuhyme  cells  o|  the  emliryo  are  the 
parents  ol  most  ol  the  connective  tissue  cells  of  the 
aii.ilt  organism.  The  latter  have  lon^  been  known 
to  be  more  or  Kss  mi^ratorv  inuhr  ceitain  comli- 
tions,  and  the  recent  work  on  the  iiiltivation  ol 
tissues  outside  the  l)od\  has  shown  that  they  pos- 
sess considerable  power  ot  anid'boid  mo\emcnt. 
When  a  piece  ot  tissue,  especially  from  an  embryo 
or  youn^  animal,  is  mounted  in  a  hanu;in^  tirop  of 
blood  pl.isma  there  soon  a|>pears  around  it  a  rinj,^ 
ot  niore  or  less  spindii. -shaped  cells  radiating  into 
the  surrounding  medium.  I  hese  spmdie-shapeil 
cells  .lie  derived  mostU  Irom  eonm.five  tissue,  and 
the  rinj^  that  is  tormed  results  (.liiellv  t  rom  the  out- 
wandering  of  cells,  although  in  some  cases  the 
^^rowth  anil  multiplic.ition  of  cells  undouluedly  con- 
tribute to  Its  formation.  The  writer  has  otten 
w.itched  the  movements  of  tliese  cells  under  the 
microscope.  I  he  huomotion  is  essentially  aiiKr- 
boiil,  and  the  cells  show  a  [pronounced  thi^motaxis, 
or  tendency  to  keep  in  contact  with  solivl  bodies. 

The  pigment  cells  ot  many  animals  are  related  to 
o)nnective   tissue   cells   both   in  oriy;in   and   mode   of 


ill,    liilltl.l'l 


,f  ( ,  //> 


l^.\ 


>i.li;i\  mr 


In  m.iMV  crustiucans. 


,l!U 


>tik's    tlu     I 


I'n'incnt    iflls    .ipi'C.ii 


!h'    ruhly    \ 


)rii\ 


tishcs.   ampliil'iiiiis 
.It   times  t<i 
anil 


iiUa    with    ImmikIicI    processes. 
iK    ;ill  iIh   piunatU  appcarv 


at  other  tunes  near 

o.neentratea  in  a  rounded  .nass.  These  changes 
..tUM.  prodiue  Miarkcd  ehannes  in  the  color  ol  the 
,„i,„,l.  Thev  .ire  to  a  eertain  extent  inuler  the 
omtrol  ot  the  nervous  system,  hut  thev  mas  al-' 
take  plaee  Inaepenaently  of  nervous  mlluence.  I  he 
writer  has  sueeeedeJ  in  isolating  pigment  eells  tron» 


I  1.,.    V. 


Sin<i'^>'o-    (  I;  iii}.'!-^    ill    Ihr 

iill  l'ri>iii  .1  t'r''^-' 


fdPIll    nf    HI    i-"l  itiil     I'lKII"'!'' 


il   also    from   the   a 


various   amphibian   larva-   and   also   irom   ....   .ulult 
tn.K'  and  in  keepinjr  them  alive  in  han^in^r  drops  ..t 
Mo..a  plasma  where  their  various  .han^es  m   form 
o.uKl  he  followed  with  the  ^r.xatest  readmess.      I  he 
pimnent  cells  were  seen  to  underjr.,  changes  m  form 
similar   to    their   ehan^rcs   in    the    skin,    puttm^^   .,ut 
pn.ccsses  here,  drawing;  them  in  theie.  and  m  some 
cases  creeping  alo-.^r  the  eover  ^hs.   for  a  consid- 
erable distan^  e.     These  cells,  like  their  relatives,  the 
connective  tissue  cells,  have   a  stron^r  positive  thi^- 
,„otaxis      I  -och  found  that  in  the  embryos  ol  the  tisM 
lundulus  thev  tend  to  appear  alon^^  the  course   of 


MICROCOPY    RESOLUriON    TEST    CHART 
ANSI  ond  ISO  TEST  CH/.P'  s,     ? 


1.0 


I.I 


28 

32 


i^ 


Ilia 
III 

2.0 
1.8 


1.25 


14 


1.6 


^    ^ppi  iFrT  :■^ 


•'Ml 


I  S4 


.S///J/Vv   /;/   .lu'nndl   Ihlunior 


the  IiIoikI  \isscls  of  thf  yolk  sac,  tncrcbv  producintr 
a  iiTtain  color  pattern  (.liaractcristic  of  the  species, 
a  result  probably  due  to  some  tropisin.  either  a 
chemotaxis  toward  oxy^n-n,  or  a  thifrmotactic  re- 
action to  the  walls  of  the  blood  vessels. 

Both  connective  tissue  cells  and  pijrment  cells  when 
isolated  tend  to  withdraw  their  processes  un- 
der unfavorable  conditions  and  assume  a  spherical 
torm.  Too  hijrh  a  temperature  tends  to  cause  this 
respf)nse,  and  the  same  reaction  commonlv  results 
when  the  culture  medium  becomes  contaminateil  by 
the  accumulation  of  metabolic  products.  An  Ama-ba 
under  similar  conditions  behaves  in  essentially  the 
same  way. 

As  is  well  known,  the  cells  of  epithelial  tissues 
are  almost  always  arranj^ed  in  definite  layers  one 
or  mf)re  cells  thick.  Such  tissues  are  found  cover- 
injr  the  entire  surface  of  the  body,  and  lining  all 
the  inner  surface  of  the  alimentary  canal  and  its 
\arious  appended  organs;  epithelium  forms  the  in- 
ner lining  ,,f  the  body  cavity,  the  blood  vessels  and 
lymphatics:  in  fact,  in  almost  every  situation  in  which 
a  free  surface  occurs  it  is  co\eretl  by  a  layer  of  this 
tissue.  It  for  any  reason  a  part  becomes  denuded 
ot  Its  coating  of  epithelium  it  is  usually  rapidly  cov- 
ered again  by  extensions  of  this  tissue  from  con- 
tiguous areas.  There  have  been  \arious  opinions 
as  to  just  how  this  extension  is  brought  about.  Sev- 
eral investigators  have  concluded  that  it  is  mainly 
ehected  by  the  migration  of  epithelial  cells,  and  the 


The   Bchaiior   of    (-fH^ 


i8s 


recent  work  ..t  I-co  Loch,  Oppcl  and  Harrison  tends 
s'  .  -iglv  to  contirni  this   view. 

V  particularly  favorable  method  of  study.nji  the 
pr:,blen.  is  presented  by  the  cultivation  ot  cp.thel.al 
cells  in  some  nutrient  medium  outs.de  the  body.  1  e 
writer  has  en.ploved  this  .Method  m  tne  study  of  the 
cpitheliu.n  of  larval  and  adult  a.nph.b.ans.  It  was 
found  that  a  piece  of  epithelial  tissue  kept  ...  a  han^^- 


IK  (Ntrnai  ir    .'..'11^'  .111(1   iH-tw.'.ii 


111.-   I 


Ink    I  irt    n-prr 


iits    till- 


.iiltivattil  ill  lyiiipli- 


In.     :,.     Stramls   of   fJuUiclliil    ( f 
'filxTS   of   cotton,   tt    .111(1    ft' 
„utK'ro«tli  from  'i  i'i.cf  "l  •'  "■">-'  '^"'1" 

ing  drop  culture  soon  showed  a  fringe  of  fattened 
cells  extending  into  the  culture  .ned.u.n.  In  so.ne 
the    area    of   the    extending   t.ssue    was   o\er 


cases 


1  xam- 
lar- 
tine 


twenty  ti.iies  that  of  the  implanted  p.ece. 
ining  with  a  high  power  of  the  .nicroscope  the  .nar- 
.in  of  the  epithelial  extension,  nu.nerous  very  1  me 
processes  or  pscudopodia  were  seen  extend.ng  m  the 
direction  of  .novcn.e.tt.  These  processes  were  seen 
U,beinc,mstantcha..ge.  Ihey  are  the  act.ve  agu.  s 
in  causing  the  sheet  of  cells  to  be  pulled  out,  tor    hc> 


arc 


both   adhesi\e   and  contractile. 


Ic.       Ihe    effect   ot 


iS6 


StJidii-s   ill   .  Ill/Ill  III   liihiiiinr 


their  activity  is  to  cuisl-  cpitlulium  to  sin-c;ul  more 
and  more  wiiicl).  ami  in  several  preparations  tliat 
were  made,  praeticallv  ail  of  the  available  solid  sur- 
face was  covered  by  an  investment  of  epithelium.  If 
individual  cells  are  isolated  they  freciuently  spread 
in  every  direction  until  tliev  heu.me  flattened  to 
an  extreme  thinness,  and  I  have  observed  scattereil 
individual    cells    flatten    out   until    the    ailiacent   cells 


I  I...  '..     .s„.-.Ts.,u.  .t,,p  .  „,  th..  .wK;,,, f  ,,   ,tra„(l  of  ..|,ill„.iiMl 

M-.,,.  th.-  r,;,!  „!■  th.-   slr.n.l    !>,„;:   I„.|«,.,,,   ,|,,   ,„-„   ,ii,..r,",„- 
'■""','"   '   :'"''   '     ^1'"""   "'    '■'-'■  •"'■      ri„-  .l,,t|,,l   li,,,.   i„.|i..,,|..,   ., 


/net.  forming  a  continuous  membrane,  scarcely  liis- 
tin,t,aiishable  from  certain  epithelial  membranes  found 
in  the  body.  I'lu  marked  thii,nnotaxis  of  these  cells 
leadin^r  them  to  s|)read  over  surfaces  ami  to  keep 
in  closi'  contact  with  one  another  is  a  verv  im- 
portant factor  in  brin^rjnir  about  the  layered  arranj^e- 
ment  characteristic  of  epithelial  tissue,  as  well  as  in 
causm^  this  tissue  to  f,.rm  a  coatinjr  ,,vcr  the  ex- 
posed surfaces  .d'  nearlv  all  orj^ans  of  the  body. 
l-|)ithelial  membranes  usually  form  surfaces  of  se- 
eretion    and    absorption    which    separate    regions    of 


77/      li,li,iiiui    -/■  r.7/> 


is- 


aiHircnt  nsmntic  pressure.  It  is  i-ssuitial  t.'  llie  pcr- 
t,.rmamc  of  mativ  important  tuiuti-.n.  tliat  tlicsc 
nicmbrancs  I'c  ahsolutcly  continuous  with  no  aper- 
tures at  any  point.  'I'his  continuity  is  insured  throu^rh 
the  traits  of  heha\ior  \vc  have  mentioned. 


A  B 

l--,,.    i        \   -.■.otHlarv   MMiiiWrM.,.-    f..n,M,l   l.y   Um-   a|.i.n.xi,n,.li.'n   ..f 
'ori.'inallv    i-l,,liMl   r,-lU    Irn,,,   \Ur  .■.l...l.nn   nf    IIvIm.   mhI.   m. 
sh.nsn    in    11.      V.-r>     tiiu-    ].     ,i.ln,„Hl,,,    :.n-   ^houn    n,    th.-    trr.- 
tiiarjiius. 

One  very  ^rcneral  and  important  feature  of  bod- 
ily organization  therefore  is  traceable  largely  to 
certain  peculiarities  of  the  behavior  of  cells.  In 
,nany  animals  the  sex  cells  arrive  at  their  tmal  post-, 
tion  only  after  considerable  migration.  in  the 
spong  s  thev  are  derived,  from  am.i-boid  cells  and  m 
hydruids  they  often  migrate  from  one  germ  layer  to 


i88 


Sii(ilrr<   ill   .hiinidl   BcJun'tor 


aiKitluT.  In  the  cf,f;j^s  oi  rnnny  insects  ulicrc  thcv  arc 
(iittrrciitiatcd  \cry  early  in  iie\  elopment  tliev  ha\e 
been  oliserxed  actually  to  pass  outside  the  cniliryo 
tor  a  time  only  to  wander  back  a^'ain.  Ileyner  has 
jierforined  the  experiment  of  rem()\iri^r  these  cells 
at  the  time  tliey  passed  f)ut  of  the  e^^  ami  found 
tliat  no  sex  cells  developed  in  the  resultint^  ani- 
mal. In  the  embryos  of  several  of  the  lower  ver- 
tebrates Dr.  B.  M.  Allen  has  found  that  the  sex  cells 
arise  in  the  entoilerni.  Then  they  wander  out  alon^ 
the  rudiment  of  the  mesentery  anil  take  u|)  their 
final  position  at  a  considerable  tlistance  from  their 
point  of  orifj;in.  .As  to  what  causes  the  movements 
ot  these  cells  and  guides  them  in  their  course  we 
can   only  offer  but   very   tentative   conjectures. 

One  of  the  most  remarkable  features  of  ilexelop- 
ment  is  the  way  in  which  ner\e  fibers  j^row  out 
from  the  central  nervous  system  and  push  their  way 
between  \arious  masses  of  cells  to  becottie  eon- 
i^ecteil  with  the  proper  eiul  orj^ans.  The  organism 
is  permeated  with  a  network  of  these  fibers,  spun 
out  as  tine  as  gossamer  threads  aiul  connectetl  with 
one  another  ami  with  various  parts  of  the  organism 
in  a  \ery  intricate  way.  In  order  to  build  up  this 
elaborate  arul  delicate  system  the  nerve  fibers  as 
tbev  grow  out  from  the  (,le\  elfiping  brain  anil  spinal 
cord  must  take  the  right  paths  and  connect  par- 
ticular groups  of  cells  in  the  central  nervous  sys- 
tem with  corresponding  parts  of  the  boiiy.  Should 
nerve   fibers   not   fintl   their   proper  termination    all 


sorts  (.f  tuiiLtional  J.isturbanccs  would  result.    What 
is  it   that   ^miJcs   the   nerve   fibers   to   their   proj^-r 

^oal? 

One  widely  accepted  theory  of  the  development 
,,f  the  nerve  fiber  is  that  it  represents  an  (nit^rn.wth 
from    the    nerve   cell.      Harrison   by   cultivating   in 
hanjring  drops  of  lymph  small  pieces  of  the  nervous 
tissue    from   amphibian   embryos   has  been   able   to 
observe  the  actual  outgrowth  of  nerve  fibers  from 
the  ganj>:lion   cells,   and  to   study   various   stages   m 
the  process  of  outgrowth  in  living  material.     Har- 
rison observed  that  the  extreme  tip  of  the  outgrow- 
ing nerve  fiber  was  often  expanded  and  irregular 
in  contour,  and  that  it  underwent  amttboid  changes 
as  the  fiber  extended  through  the  lymph.     It  is  not 
irnprobab'e  that  this  ama-boid  activity  is  the  cause 
of  the  drawing  out  of  the  nerve  fiber.'     The  factors, 
chemotaxis,  thigmotaxls,  or  whatever  they  may  be, 
which  direct  this  ama-boid  activity  may  be  respon- 
sible  therefore    for    the    distribution   of   the    nerve 
fibers  in  the  body  and  the  establishment  of  the  nu- 
merous connections  that  occur  within  the  nervous  sys- 
tem  itself.      The   architecture   of   the   nervous   sys- 
tem,  the   great  controlling  element  in  behavior,   is 
r.ot  improbably  itself   a   product  to   a   large   extent 
of  the  peculiar  behavior  of  its  component  cells. 

1  I  h  It  the  iiirvf  t'lbtr  is  actii.tlly  <lrawn  mit  in  the  way  sti^- 
uc^l.d'ha.  recently  hctn  shuwi.  hy  Mr  J.  C  Johnsun  >n  h.s 
.tudie.  of  th..  ner^c  cells  of  atTiphihiaii  larv.v.  Krterciice  may 
l,c  made  t..  his  i^i-er  on  "  ihe  Cultuattun  ui  1  .^m.o  .■■  Am- 
l.hihians,-  iHll.H^hed  in  the  I  mv  of  Cahl  I'uhl  /.ml.  Vol.  10. 
I>    55.   1915- 


!  ()l) 


•S ///(//(  >    ill   .hiinuil   liilutiinr 


.\i7i(.n^r  the  most  motile  of  the  cells  ot'  the  body 
;u-e  the  leiKoevtes  or  wliite  hh.oii  eorpuscles.      These 
(clls   are   very   mmh    like    Amah.c    in    their   appe.ir- 
aiue  ami   their   aitivities.       I'liey   have  the   property 
ot   creepiii;,r  ;,li,,ut  in  the  various  spaces  ot'  the  hoJv 
ami   of    passin^r   tlirou-li    tlie   Jeiieate    wails   of    tlie 
capillaries.      I  jieir  power  of  eni;ullim;  bacteria  ami 
fra^nnents  of  l)rokeii-ilou  ii  ceils  is  well  known.      I  hey 
act  not  only  as  tlie  scaven<,rers  ..f  the  boJv,  but  by 
virtue    ot    their    power   of   liestrovin^r   bacteria    they 
ileleiui  the  lioiiy  aj^ainst   various  disease  L,a-rms  that 
constantly    invade   it.      Apparently    they    are   drawn 
to  centers  ol  bacterial  infection  l>v^a  sort  of  chemo- 
taxis.      I  his  is  shown  b\  an  in^renious  experiment  hv 
Massart    in    the    foiiovvint,r    wav  :      .\    tul'e    of    cul- 
ture medium  containin^r  ;,   culture  of  the  bacterium 
StaphyliHinno  />\iuj,-iif.^   alhiis   was  introiiuied   into 
the  abdominal  cavity  of  a    rabbit.      After  a  time  it 
was  fouiui  that  the  leucocvtes  had  wandered  into  tlie 
tube  in  iar^re   numbers.      A   similar  tube   tiileii   with 
the    same    medium    but    containiii^r   „()    bacteria    was 
also  introduced,  but  it  was  not  entered  bv  the  leu- 
cocytes.     It   is  probable,   therefore,   that  some   suli- 
stances    proiiuced    by    the    bacteria    caused    the    leu- 
iDCStes   to   enter   the   tube. 

1  lie  species  ot  bacterium  used  in  the  ex[ieriment 
is  one  ol  tile  common  forms  that  ^ive  rise  to  the 
production  of  pus.  Iliis  sulistance  which  so  fre- 
(luentiy  ^r;it|it.,-s  in  inllanied  areas  is  [iroduced  mainly 
by   dei^rene rated   leucocytes   which   have  accumulateil 


Tlir    liiluiiior   "/    (-I'li^ 


\>)\ 


at   the    scat- of   injury.       I'Ik-    a^tircjration    <.t    these 
w.uuicrin;^  tells  j.uy  aetuallv  he  ohservevl  utuler  the 
inierosu.pe   in   th.    transparent   livin^r  mesentery    .it 
tlie  troK-      "  -1  P'>''f  "'  ^'^^"  "icsentcry  is  drawn  out 
,,t    the  livin^r  animal   and  strctchetl  over  the   sta^e 
n\  a  inicroscope  the  blootl  iiuiy  he  ohserved  stream- 
mn  through  the  capillaries,  and  the  individual  lor- 
puseles  distinctly  followed  in  their  course.     It  a  re- 
^um  near  a   capillary  is  pricked  with   a  hot  needle 
the  white  corpuscles  may  be  seen  to  pause  in  their 
course    as   thev    arrive    near   the    injured    area    and 
pass  throujrh  the  capillary  wall.      Here  aj^ain  it  is 
probably    some    chemotactic    proclivit>'    that    causes 
tlie   leucocvtcs  to  congregate.     Combined   with   the 
p,,wer  of  these  cells  to  devour  bacteria  this  chemo- 
tactic  tendency   enables   the   leucocytes   to   phiv   the 
part   of  watchful  protectors   in   checking   infections 
and  destroying  products  of  decay. 

Besides  their  role  in  maintaining  the  normal  ac- 
tivities  of   the   body   the   leucocytes   often   play    an 
i,ni)ortant  part  in  development.      In  the   formation 
of  an  organism  the  tearing  down  of  previously  es- 
tablished structures  is  often  a  necessary  preliminary 
to  further  advance.     The  resorption  of  the  tail  of 
the  tadpole  is  a  process  of  involution  in  whi.h  the 
leucocytes  play   an   essential   role   in  destroying  the 
fragments  of  the  degenerating  structure.     'I  lie  or- 
gans oi  the  caterpillar  are  very  largely  destroyed 
in  the  (luiescent  pupa  state  in  which  the  reorganiza- 
tion of  the  body  occurs  that   results   in  the   forma- 


192 


.V,7,7/.  V    ///   .liiiu'.iil   liiliiiiior 


tion  u\  Mul,  ;,  v,.,.y  tilth'!  cut  criMturc  ;is  tlu'  hut- 
tcrlly.  1  In-f  .ells  inu^li  like  tlu'  lcm-iK\tcs  act  as 
ilcvdiiriiii;  ^Hs  ,,,•  plia^r(.t\  tcs  wliiJi  ciij,nill'  tlic  ma- 
terials (it   t!ic  ijci,'!.  iicratin^r  tissues. 

Appai-eiitU-  the  Kiiukytes  are  omiiixorous  in  their 
appetite.      One  n\   ni\    inniier  stinleiits.    Dr.    I'asten. 
who   has   m.ule    a    t!inr(.UK^Ii    stmiy   ot'   tlie    iKJunior 
of  these  eells,   tiihK   that  they  enjriilf  i\en   >ueh  suh- 
staiues  as  sulphur  arij  ehrome  vellow,  which  uouKi 
be  rejeitei!  In    an    XiiM'ha  nr  almost  any  other  free 
organism.       i  his    inJiseriminafe    appetite    wouKl   he 
fatal   to  a   ereature   !i\int,r  a    free   life.      I'rohahly  it 
IS   not    partuularly   i.,r,„„l    t,,,.    (j,^,   Icueotvtes;   hut   it 
must  he   rememlnreJ   tliat  the   r<Me  of  these  cells  is 
primarily  altruistic.      Thev  work  for  the  welfare  of 
the  hoiiv   physiolo;^ri^al.       The)    are    reproJuceJ   not 
so  much  from  other  leucocytes   (although  this  [)roc- 
ess  occurs)    as  h\   the  JMsion  of  eells  in  hone  mar- 
row  and   certain   other   or}.,rans   of  the   hody.      They 
are  meant  tor  sacrilice  after  a  lil'e  of  ser\  ice.     .\nd 
Nature    has   made    them    rather   more    than    usually 
unmimlful    of   their   iihlMdual    welfare. 

llowexer  these  cells  do  show  mam  of  the  pur- 
[)osi\e  reaaions  so  lommoiily  found  in  f|-ee  orjran- 
isms.  Dr.  hasten  In  a  delicate  a[iparatus  has  suc- 
ceedeti  in  hrin^ini;  the  point  of  a  \cry  tin.  {r|ass 
rod  against  one  side  of  the  cell.  The  leucocyte 
thus  irritated  [uit  out  pseudo(iodia  opposite  the  point 
ot  the  rod  and  crejn  away  from  the  stimulus.  The 
method  ot  response  was  practicallv  the  same  as  that 


/■//,    H.lmii"!    "t   ('■>  I!' 


^•)\ 


,,|  ,111  \m(il);i  iiiulcr  tin-  same  iDiulitions.  \  kv 
\mii'h.i  alxo  tlic  Iciiiocvtcs  wore  fouiul  t.)  he  Mf«a- 
ri\c  ill  their  n^ponse  t<>  Ui;lit,  ami  uIumi  MiSjcaol 
t.  too  \\\^h  a  ili-ijrrL'  of  heat  th^v  uilharcu  their 
psciulijpoiU  atul  a^sumc^l  a  roumied  lorm. 

It  woiilii  he  i>t  interest  to  ascertain  how  the  vari- 
ous other  moviM|,r  cells   react   to   dittereiit   kinds  of 
stimulation.       I    have    tried    the    ettect    of    loeuli/cd 
mechanical  stimulation.  li«ht.  and  heat  on  piirnient 
cells,   einthelial   cells   and  cells   from   connective   tis- 
sue, hut  found  no  reaction  to  lij^ht,  no  inarkeil  ten- 
dency to  crawl  away  from  injurious  mechanical  stim- 
uli, hut  a  general  tendency  to  round   up  under  too 
hijrh    a    degree    of    temperature.       Ihe    trecly    wan- 
dering  tissue    cells    ilo    not    appear    to    possess    that 
repertoire   of    adaptive    responses   which   iiie   leuco- 
cvtes  have  in  common  with  the  .\m<rha.     IVohahly 
fuller   inx.M.K^tion   will    reveal    more   adaptive  he- 
havior  in  tlie  cells  of  many    forms.      We   -"<>«■  as 
yet  next  to  nothing  in  regard  to  this  iield  ot  mciuiry, 
hut  it  is  one  which   promises   to   attord   interesting 

results. 

In  that  fascinating  group  of  primitive  organisms, 
the  slime  moUls,  formative  processes  stanil  in  a  more 
ohvious  relation  to  cell  hehavior  than  in  the  higher 
organisms.  The  coming  together  of  individual  cells, 
their  union  to  form  a  creeping  plasmodium  like  a 
gigantic  Ama-ha,  the  transformation  of  this  plas- 
modium into  a  definite  form  characteristic  of  a  par- 
ticular species,— all  thes^-  prcjcesses  are  f<jr  the  most 


">4 


Stutlhy    in     liiinidl   Hrliaii'ir 


I  art  in.ittLr-,  n\  thr  !n.li:i\  inp  <it'  (.rlK.  Il  u  r  cm 
inti.  ipnt  ill  \(.l(i|>im  lit  aiuulicrc  in  terms  ol'  tin 
lrn|iisms  ;m(|  orlur  risii().isi.s  ut'  iiuli\  itiu.il  nils  tliis 
priiiliar  j^M-cmp  nl  oij^'aiiisms  woiiKl  sciiti  to  prcsfiit 
iinusiialK  la\nia!)l(.'  (ippuitimitics  for  attaikinj;  the 
pmhlciii. 

In  a  \cr-,  intirLstin^r  !,crii.s  of  cxpcrinutits  I'rot. 
II.  \  .  W  llsoii  has  uit  \arl(uis  sponges  ami  hyilro'uls 
itito  pieces,  pressed  the  tissues  throii^^h  fine  bolt- 
in;,'  eloth  so  as  to  reduce  them  praetieally  to  masses 
ot  isolateii  cells.  It  was  found  that  these  cells  he- 
^Mn  to  come  together  ani.1  form  a)j;^ri-i'^ati()ns  which 
subseijuently  iliHcrentiated  into  the  form  of  the  spe- 
cies trom  which  the  fraj^nnents  were  taken.  Out 
ot  a  hodi^re-pod^re  ot  all  sorts  of  cells  one  sees  the 
;.,'radual  emerj,'ence  of  an  organic  body.  The  pro- 
ponents of  the  conce|nion  of  a  cell  state  could 
scarcely  hope  for  a  better  illustration  of  their  point 
ot  \iew.  It  is  as  if  a  ^roup  of  independent  cells 
had  said  amon;,r  themseKes:  "Behold,  let  us  creep 
to^a-ther  and  torm  an  organism.  il  some  of  us 
do  this,  some  that,  anil  others  somethiiijr  else  wc 
will  all  ^ct  alon^  in  pe.ice  atul  harrjionv  ami  more- 
o\er  much   to  our  mutual   ad\  antaire." 

I  low  a  cell  ditlerentiates  as  well  as  what  it  does 
in  the  \\a>  of  l^'haxior  depemis  largely  on  the  re- 
lations in  whicli  it  stands  to  other  cells.  I  he  di- 
rection ot  difterentiation  which  a  cell  follows  may  be 
lookeil  upon  as  a  response  to  environmental  stimuli, 
just  as  the  movements  of  a  cell  may  be  so  regarded. 


Rifcri'uiis 


I'H 


,H,  ,,H.r^,v  cv..Ivch1  as  ;,  u.n.o,uc,KC  ot  st.MU.l.U...,, 
„v,v  be  cmplnvol  .nainly  in  yvo^u.u^^  structural 
,,,:,;ii,icationsof  thc.cllsuh.ta,K..  .>rit  mavW.v 

pcuka  .nainlv  in  pr.uhKinp;  .n-tor  rcactu-ns.  Itu- 
response   is   usuallv   purposive   aiul   soual    >m   ctlur 

''Zur  Strasscn  in  a  aisn.sslun  of  "Animal  iMuni.-r 
,,ul  DevclopHK-nf  before  the  Seventh  International 
/..olo^neal  Conjzr.ss  at  Hoston  eallcJ  attention  to 
n,e  social  bchasior  of  cells  an.l  the-  analo^r,es  be- 
tween such  behas  ior  an.l  the  activities  of  social  in- 

seets.      The   comparison   is   su^^^'st.ve     but    as   /-ur 
Strasscn  points  out.  there  is  a  closer  relationship  be- 
tween the  cells  of  the  meta/oan  body  a-ul  the  pn.- 
tn/oa,   which   are  not  improbablv  the   .hrect   ances- 
tors  of   these   cells.      Were   the   proto/oa    social    in 
thcir   behavior,    chd    the    diHerent    behaMor    of   the 
several  castes  depend  up..n  ntutual  interaction  as  it 
docs  to  a  certain  de^rree  amon«  social  insects,  the 
analogy  between  behavior  and  development   would 
indeed  be  close. 

KFFi-Ri  :nci:s 

\i,,v  H  M.  The  origin  of  the  sex  cells  of 
W.aand'l.epidosteus.     Jour.  Morph.  22.   , ,  .<>.i. 

nxKKls..N,  K.  (;.  The  outgrowth  ot  the  nerv. 
fiber  as  a  mode  of  protoplasmic  movement.     Jour. 

lloi.Mls,  S.  J.      iO  Obscrxations  on  is..latcd  l,\- 


'0^  Siud!,-.    in   .hii,u,,l   /Irhriiiur 

inir  pll^in.nt  alls  fn,,,,  th.  Ian.,  ut  amphihi.Ms 
niv.  „l  Calif.  i'ul,s.  /,„,!.  ,,,  ,4,,  ,,,,^.  (3)  H,.; 
hanor  ,.|  ,ct,u\cruuc  .pithdlun,  of  ta.lp,,Ics  uhcn 
culriNatcci  ,„  plasii-a,  I.  c.  1  1 .  1  ;-.,,>  1  ^  <  r^)  -fh,. 
mnvcrmnts  anj  reactions  „f  iM.lat.J  inelanophcrcs 
"  tu-fn.;,.  I.,.  ,^,  ,,,-  ,,^,^  ^^j  The  behavior 
of  the  .pnicrnus  o(  aniphil-Kins  when  cultivated  out- 
si.le  the  h.ulv.     Jour.  Cxp.  /<.,].    ,7.  2«,.   h;,4 

'"";•  J-  <)n  the  hereditv  <.f  the  markin^r  i„ 
-sh  cmhrvn.  Biol.  I.etures.  .Marine  Hiol.  I  ah. 
\V  (Hxls  I  li.le,   I  S()<), 

M^-^-<l,  J.,   and   H,,.,,,,.   c.      Rechcrches   sur 
lM-r,r,:h,htedcsKuc,KNtcs,  etc.     Jour.  Sue.   kov.  Sci 
Med.   et    Nat.   .ic    Hr;ixcl!es,    iS,)n. 

,/■'■''"•  '^^  ^•'"-''-">'"Tl">lo^risehe  Studien.  IV 
A'.ttnun.  Arch.  f.  I  ;,H..-,„.,h.  ,4.  LU-  19..; 
V    AlitteduiiLT,  I.  c.    ;;;,  371,    ,,^[,. 

,  !''''"';.  ^'  ^  ''"'■  '''^'  '^^■^.^^•'i^''-ati<)n  des  Kpi- 
tMsder  Cornea.    \..h.  nnkr.    \nat.  .^.^    ,,^,    ,s,s.;. 

,.'","'■•  ^V'-  ^'^■'^""  ''"'  <^'ytotropismus  der 
i'"vh„n.:.rs/clleM  .les  (  .rasfrosches.  Arch.  f.  l-'ntw- 
tnech.  I,   1  ,S(;4. 

,  ^^■";."^-  "•  V.  M)  Dcvch.pment  of  sponj^es 
^roM,    dissociated    tissue    cells.       iJuIl.    Bureau    Fish- 

"'T\""u"''\r     '^)     ilK'  behavior  of  the   disso- 
ciated cells   ,n   Ifvdmids.    Mcvonaria.  and  Asterias 
J"ur.    I  xp.   /,„,!.    11.    2S,>.    19,  ,. 

'f-^^<  Mk\ss.x.  II.  AniuKd 'behavior  and  de- 
;-l"Pn)cnt.  I'roc.  7rh  Internat.  /ooi.  Con^n-ess, 
ijosfon,    K)  I  1.  "J 


XI 


I  111.    INSl  l\i    1     <'l      II  It.MN'-    I>1  ^l  " 


Till'   so-callca  instinct  of  ffii,minu  death   is  one 
which   is   \crv   wiady   distributccl  In   the   animal 
kingdom.      It  er.'.ps  out  sporaaicallv.   as  it  were,  in 
forms  which  are  but  very  distantly  rehited.  and  hence 
It    must    have    been    indenendentlv    evolved    a    ^'fcat 
many   times.       The    e\iM-essin:i    feignini^r   death   is   a 
misleading  one  to  the  extent  thai   it  is   apt  to  give 
rise  to  the  idea  that  the   animal   consciously  adopts 
this   device   with   the  Intent   to   deceive.      But   while 
it  is  probaole  that  am.uig  the  higher  animals  which  ' 
sometimes  feign  death  there  may  be  an  attempt  to 
mislead  their  enemies,  it  is  quite  certain  that  among 
the  insects,  spiders  and  other  low  forms,  there  is  no 
such  aim  in  the  creature's  mind,  if  we  grant    (what 
some  naturalists  are   disposed   to   deny)    that  these 
animals  have  minds.     The  unpremeditated  character 
of  this  peculiar  behaxior  was  tirst  shown  by  the  ex- 
periments of  Fabre  on  beetles.      In  order  to  ascer- 
tain  if  the  duration   of  the   feint   was   m   anv   way 
affected  bv  his  own  mo\  ements,  I'abre  made  several 
observations  on  a  large  carab  beetle,  Scaritcs,  which 
shows  the   death    feigning  instinct   va   a   pronounced 
,nd  tvpica!  form.     When  handled,  the  beetle  would 

i'>7 


ivs 


•W.7,//Vs    ///   .lunmil   lliluiiinr 


""■""    " ""'   i'""   ;i'i    i,nMi,.I,iIc    st.itc-    uirh    its   head 
^•''f  'f"un  :incl  its  It.i^s  ,lr;iun  in  close  to  r!ic  Ix.ilv. 
ft  uuuM  r.MKiiii  In  this  attitude  pcrtVctIv  .jiiict  f.'.r 
sc\eral  nnnutcs— sumctirn,',  for  over  an'hour.      Its 
auakeninfr   would    !,e    Hrst    manifested    hv    a    slltrht 
trcn.hlinjr  of  the  feet  and  a  slow  oseillation  of  the 
antcnn.T  and  palps:  then  its  ie^s  would  move  about 
"I'Tc   MKorouslv.  an.!  finallv  the  insect  would  arise 
and  scamper  off.     Seized  a-ain.  it  would  repeat  the 
perforntancc   se\eral   times  in   succession,   the  dura- 
tion   of    the    feint   often    increasing    with    successive 
tnals.     iinally.  as  if  wearied,  or  con\  inced  that  the 
ruse    were    \ain.    the    beetle    would    refuse    to    feign 
longer. 

_  Were  the  feints  attempts  to  deceise  its  captor  by 
simulatmg  death?      labre   placed   t!,e    insect   on   its 
back,   went  to  a  distant  part  of  the   room,   and   re- 
inamed  perfectly  .luiet.     The  beetle  still  lav  as  usual. 
1  Ic   then    went  out  <if  the    room,   carefullv    looking 
"1  at  intervals  to  watch  the  course  of  events.     Still 
tile  same  immobility.     In  other  cases  he  covered  the 
insect  so  that  it  could  not  see  out  and  then  .juietly 
u-  mt  away.     This  was  also  found  to  make  no  dif- 
ference.      In    f;ut,    whether    the    insects    were    sur- 
rounded b\   sounds  and  sights  of  moving  objects,  or 
cntirelv  excluded  from  these  influences  made  no  dif- 
Krence   in   the   average   length   of   time   thev   would 
remain    m   a   motionless   condition.      Similar   experi- 
ments ha\e  been  made  on  other  insects  bv  different 
ol)servers,   who   have   all   ..rrived   at  the   conclusion 


riu    In.-lhhl   "(   l-'iii/»iihj    DtUth 


199 


that  ciiiisciou^  iKwptinn  pl.iys  tm  p;ut  in  the  process. 
The  aititink-^  ;ismiiiu\1  by  inscits  ami  other  forms 
when  I'eij^niiiij^r  J.ath  are  usually  ijuitc  diftcreiit  from 
rhose    of   ilead    s|Keimeiis.      This   general    taet    was 
pi.ii'.teii  oi't  In    Darwin,  who  says  that  "I   earetully 
note.l  the  sinuilateil  positions  ot   se\enteen  J.itterent 
kinJs  of  insects  i  incUk'-iii^  an  lulus,  spider  and  Onis- 
cus)    helon^in^   to    distinct    genera,    both    pioor    and 
first-rate  shammers:  afterward  I  procured  naturallv 
dead  specimens  of   some   of  these   insects,   others    I 
killed    witii    camphor    by    an    easy    slow    death;    the 
result  was  that  in  no  Instance  was  the   attitude  ex- 
actly   the    same,    and    in    se\eral    instances    the    atti- 
tudes of  the   feit,niers  and  of  the   really  dead   were 
IS  unlike  as  they  possibly  could  be." 

■j'he  attitudes  of  animals  in  the  death  feint  are 
fre(|uentlv  \erv  characteristic.  Many  beetles  as  well 
as  other  forms  fei>j;n  with  the  lej^s  ilrawn  u{)  to 
the  bodv  and  the  antenn.f  closely  appresscil,  so  that 
the  whole  insect  assumes  as  compact  a  form  as  pos- 
si!-Ie.  The  woodl<'"se.  Armadillo,  rolls  itself  up  into 
a  ball  with,  its  k\u;s  drawn  into  the  center,  a  habit 
which  li,u.  doubtless  caused  the  name  pill-buLi  to  be 
L;i\en  to  this  erustacean.  A  beetle,  (ieotru[)es,  ac- 
^ordin<,'  to  KIrby  and  Spence,  "when  touched  or  in 
fear  sets  out  its  le>,rs  as  stiff  as  if  they  were  made  of 
,.,,,1  ^vi,-,^^ — which  is  their  postui'e  when  ilead — and 
remainini;  motionless  thus  deceixes  the  rooks  which 
prey  upon  them.  A  tlitterent  attitude  is  assumeii  by 
one  of  the  tree-chafers  probably  with  the  same  end 


2t)i) 


Sl/iili,  '.    Ill   Jiiiiiittl   HtluiiKir 


m  view.  It  soiiKtiiiics  elevates  its  postcricjr  legs 
into  the  air,  so  as  to  form  a  straij^ht  vertical  line, 
at  rifrlit  aiij^rlcs  with  the  upper  Mirface  ot'  its  hoJv." 


I"i'-..   H.      I.iirv.i    of   ,1    -.■oiiiclrid    innlh    .il|;i,|„.(l    to   ;,    t«ij.'. 

Spiders    usually    f'eiirn    hy    foKlinjr   up   their    le^rs, 

'uroppin^r    Joun,    aiui    remaining;    motionless.      The 

caterpillars  ot    some  of  the  .ii;eometrid  moths  lia\c 

the  curious  hahit  of  attaehiiij;  themsehes  to  a  branch 


I'lir   Iit.^liih  t   of   Fcujiiiiuj   Drath 


20I 


hv  their  posterior  Icujs  niiil  hoKiinir  the  hojy  straight 
and  stiti  at  an  an^le  to  the  stem,  thus  forming  a 
remarkahly  close  rcsenihhuue  to  a  short  tui^.  1- re- 
(jucntlv  the  iiL'cepti\cness  is  increased  by  a  nuirki-il 
simihirity  in  color  to  that  of  the  branch  to  which 
they  are  attached. 

While  in  most  cases  a  species  has  a  particular  at- 


'■'i(i.   !'.     A    uiitrr   s<(iri)iiin.   Hiiimlrn,   fi  i^'iiiii^'   di' illi. 


titudc  which  it  maintains  when  sinuilatiiifr  death, 
there  are  some  forms  which  fci^n  in  whate\er  pos- 
ture they  may  be  when  disti:rbi.d.  A  ij;ood  ex- 
ample of  this  is  afforded  l)y  the  w.iter-scorpion 
Ranatra.  This  inseit  ha>  the  two  liindcr  paiis  ot 
le^s,  which  are  cmployeil  in  walking  and  swimming, 
very  loni^  and  slender:  the  tirst  pair  are  fitted  tor 
jijrasping  the  small  atjuatic  animals  on  which  it  feeds 
and  are  carried  straight  out  in  trout  of  the  body. 
It  is  oidv  necessar\  to  pick  one  of  these  insects  out 
of  the  water  to  throw  it  into  a  stilt,  immobile  con- 
dition which  usually  lasts  sexeral  minute>  and  some- 


2f>2 


Sniili(^    ill   .liiiniiil  liilhii'tuf 


tiriK's  for  owr  an  hmir.  I'Ik'  Klts  mav  he  closely 
pressed  to  the  liojy  so  that  the  ereature  resemhles 
a  stiik,  or  they  may  stand  out  at  ri^^dit  angles  to 
It,  or  !>e  hem  in  any  position,  sonie  in  one  wav  and 
some  in  another,  depending  upon  how  thev  happen 
to  he  when  the  leint  he^an.  And  no  matter  how 
awkward  the  position,  it  is  ri^Mdlv  maintained  iinril 
the  feint  wears  oft.  I  lia\e  found  th.it  \oLing  Kana- 
tras,  the  first  day  they  emerired  from  the  eL^j^  and 
'•hile  their  appendajj;es  were  still  soft  antl  easily 
hent,  showed  tlie  same  death  feif^r,)injr  instiiut  as 
the  adults,  althouj^h  the\  did  not  persist  in  it  for 
so  lonjr  a  tiine. 

I  he  water-lui^r  iklostoma  usually  fei^ms  with  the 
lejrs  closely  pressed  to  the  thorax  or  else  held  folded 
at  right  angle,,  to  the  body.  In  Nepa,  on  the  other 
haml,  the  attituiies  assumed  seem  to  depend  mainlv 
on  the  position  of  the  legs  just  pre\ious  to  the 
death  feint,  so  that  it  is  tlitJicult  to  distinguish  a 
feigning  indi\iilual  from  one  that  is  really  dead. 
Schmiilt  has  been  able  to  make  the  walking-stick 
Carausius  feign  in  all  sorts  of  ungainly  positions 
which  would  often  he  maintained  for  hours  at  a 
time. 

Death  feigi^ng  does  not  seem  to  occur  among  the 
I  lower  invertebrate  animals  such  as  the  Protozoa, 
Cddenteratcs,  mollusis  \nd  worms,  although  some 
of  them  may  exhibit  reactions  which  are  prophetic 
ot  this  instinct.  Among  crustaceans  the  instinct  in 
its  tull\  de\elopetl  form  is  (juitc  unconmion.     Some 


Tin    hi^tiihl    nf   1','upniui    l),titli  2o^ 

MMis  a^n  I  do'-Lrili.\l  the  ik'ath-ffijruinir  of  ccrtam 
vHccics  of  terrestrial  :unphi[iod  crustaeeaiis  wliieh 
are  fre(|ueiitl\  fouiul  on  saiuK  Iieaelus  near  the  sea- 
shore. Hn  aeeouiit  of  their  pecuruir  hopping  move- 
ments these  erListaieaiis  are  eoniinonly  known  as 
sand-lioppers  or   saiui-tleas,   although   they   have   of 


].-|,,     10.       \    ^atu)   fif.i,    Tnl'irrfii  :<li'i.   ii,    tlii-   dtMlli    rciiil. 

course  no  relation  to  the  ordinary  fleas  of  human 
experieiiee.  <  )ne  of  the  lart^est  species  of  sand- 
hopper,  I'alorehestla,  is  common  alon^  our  Atlantic 
coast,  where  it  li\es  during  the  day  in  burrows 
i7iade  in  the  sand,  comint^  out  only  at  night  to  feed 
upon  the  seaweeil  anil  other  materia!  washed  ashore 
by  the  wa\  es.  When  tlie  Talorchestlas  are  dug  out 
of  their  burrows,  they  usually  lie  curled  up  with  their 


2.-4 


SiitJif.s  in  .hiimul  lit' Inn  tor 


l"nj,r  antci)M;L-  hciit  umkr  the  liojy  and  their  k^^ 
iliaun  up  M»  ;ts  to  assume  a  eoiiipaet  tunn.  They 
will  lie  Ml  this  way  tur  several  minutes,  when  they 
may  l)c  seen  slowly  to  rehix;  rhe  le^s  then  mo\c 
about,  arnl  soon  the  ereature  h.ops  away  l^y  a  sudden 
extension  of  its  ahilomen.  When  eau^ht  in  the  hand 
they  will  lei^rii  death  a^ain,  and  repeat  tlie  pertorm- 
aiue  many  times  in  >ueeession.  (  )ther  species  of 
sand-hoppers  exhibit  the  same  instinct,  thou^rh  less 
perfectly,  and  there  are  traces  of  it  in  many  of  the 
reactions  of  their  aquatic  relati\es. 

1  he  \arious  s[)ecies  of  wood  lice  exhibit  the  in- 
stinct of  fei^min^r  tjearh  in  \arious  dc^rrees.  Some 
species  are  able  to  roll  up  into  an  almost  perfect 
ball  and  will  remain  in  that  state  for  a  consider- 
able time.  Other  species  curl  up,  but  make  only  a 
\cry  imperfect  approximation  to  a  sphere,  and  they 
niay  maintain  this  attitude  for  only  a  short  period. 
Some  myriapoils  when  disturbed  curl  up  in  much  the 
same  way.  Anionj;  s[iiiiers  death-fei^rning  is  not  un- 
coiTimon.  especially  amony;  the  orb  wea\ers. 

It  is  amonj;  the  insects  that  the  death-fei^rnin^r  in- 
Istmct  reaches  its  fullest  ile\  elopment.  occurrinjr  to 
a  greater  or  less  extent  in  most  of  the  onlers.  It 
IS  especially  common  in  beetles  and  not  unusual 
among  the  but,rs,  but  it  is  .juite  rare  in  the  highest 
orders  such  as  the  Diptera  ami  the  Hymenoptera, 
or  the  ants,  bees  and  their  allies.  ft  occurs  in  a 
tew  cases  among  butterllies  and  moths,  both  in  the 
imago  as  well  as  the  larval  state.      The  instinct  is 


'///(■    !n'liii,l    iif    I', 1,1  until    Ditith  20; 


(.\liibitcil  in  iliffcrctit  species  in  all  stag's  ol  ilcvtlop- 
inciit  from  a  rnoini-ntarv  tcmt  to  a  ^onJitioii  ot  in- 
tense rigor  lastinj^  tor  o\er  an  hour. 

Ainon^j;  the  vertelirate  animals  lieath-leigning  has 
lieen  ohserveil  only  rarely  in  the  fishes.  In  the  Am-* 
pliihia  it  is  not  exhibited  iii  the  striking  w.iv  it  oe- 
eiirs  in  insects  anJ  s[>Iilers,  althougii  trogs  aiul  toads 
may  he  thrown  I)v  the  proper  manipulation  uito  an 
immobile  eoiulition  more  or  less  resemlWing  it.  \ 
}>henomenon  ap[iarently  related  to  tile  death  teigning 
of  insects  has  long  been  known  in  certain  re}>tdes. 
Darwin  in  his  .Innrtuil  nf  R,  -i  ai ,  lus  ilescribes  a 
South  .American  li/ard  which  u  lien  Irighteneil  "at- 
tempts to  avoid  disco\  cry  by  teigning  death  with  out- 
stretched legs,  ile[)resseil  body,  and  closed  eyes;  if* 
further  molested  it  buries  itself  with  great  (juickness 
in  the  loose  santl."  The  I'gyptian  snake  charmers 
by  a  slight  pressure  in  the  neck  region  are  aide  to 
make  the  asp  suildenly  motionless  so  that  it  remains 
entirely  passi\e  in  the  luunls  ot  the  operator.  .\nd 
similar  phenomena  ha\e  been  tourul  ■  other  spe- 
cies. 

In  birds  the  instinct  crops  out  o'i'\  here  anil  there. 
.\  few  summers  ago  when  on  the  island  ot  I'eiii- 
kese  I  was  somewhat  surprised  to  tiiui  rhe  instinct 
well  de\'i'lo[)ed  in  the  \oung  terns  which  were 
hatched  out  in  abundance  on  the  hillsides,  lor  a 
short  time  after  being  hatclied  the  little  downy 
fellows  betray  no   tear  ot   man  and  will  cuddle   un- 


2o6  St„Ji.s   in   .Inimal   n./niiinr 

jicr   .wk\    ha.ul    in    pcrtca    cnfiJciuc.      Wlun    the 

«.  feathers  the  instinct  ..f  tVar  takes  possession  „t 
then,  and  they  run  and  hide  in  the  «rass  when  v..u 
appn-.-uh.      Here  thev  lie  perketlv.,niet:  vou  may 

:  Pi'll  t'lcn,  ahni.t,  streteh  uut  their  le^s.  necks  or 
Winers  and  phue  the,n  ,n  the  ,n..st  aukuard  p„si- 
t'""s,  and  they  will  remain  as  lin<p  and  n.„ti<.nless 
as  If  really  dead.  Thev  uill  eN  en  sutler  their  wnnr 
'"■  tad  leathers  t,-  he  plucked  -ut  one  In  -ne  with- 
out a  wince.  lUit  all  ..f  a  sudden  the  hird  heu.ines 
a    veiv    difterent    Meature.       It    suvains.    p.eks    and 

.struuules   t.,   escape,   and   is   serv   apt   t..   succeed   on 


account  ot  the  surprisin^r  .)uickncss  ot"  the  chancre. 
I  have  made  several  attempts  to  make  a  hird  feij^m 
death  a  second  time,  hut  never  met  with  success. 


.Accordm^r    to    Couch    the    land    rail    and    skvlark 
fn^n  death,  and  \\ran«ie  states  thai  the  wild  ^cese 
of  S.hena  have  the  same  hahit  durin^r  ,1,,;^  ,„.,ni     , 
season,  when  they  are  unahle  t..  Ilv.      I  Iuds..n  states 
"1   his   most  mterestintr  A.;//,,,///,/   ,„;  //„.   /  ^,   /./,,/,, 
^  that    the    coimnon    partrid-e    ot    the    pa.npas,    when 
captured,    "alter   a    few    violent    struu^les   to    escape 
drops    Its   head,    ^asps   two   or   three    times,    and   to 
all  appearances  dies.      It.  when  v..u  lun  e  seen  this 
you  release  your  hold,  the  eves  open  instantlv.   and 
with   startlm^r  suddenness   and   roi.se  of  winjrs.   it   is 
up  and  away  and  hevond  vour  reach  forever."' 

In  mammals  W,e  instinct  is  so  well  shown  in  one 
of  the  lower  memhers  of  the  -nu,p,   the  opossum, 


The   l»>l'ni<i   nf  I'tiijniiii/   Dniili  inj 

t(i:it  the  i-xprcssioii  "playing;  possuin"  Is  f.imiliar  to 
iviry  one.  I oxcs  ulnii  trap|)cil  iir  harj  pressed 
i.lfiii  lirop  liouti  limp  arul  apparently  lifeless  arul 
will  even  eiuhire  a  ^kuiI  ileal  of  maltreatment  with- 
I'lit  making;  an\  response.  Hudson  records  that  he 
uas  "onee  ridin^r  with  a  ^aiieho  when  we  saw,  on 
the  open  le\el  j^Toiind  before  us,  a  fo\  nor  yet  fully 
yroun    standinjr   still    aiul    watehin^j    our    approach. 

\ll  at  once  it  dropped,  aiul  v.hen  we  came  up  to. 
the  spot  it  was  lyin|,r  stretvhed  out.  with  eyes  closed, 
and  apparently  dead.  Mefore  passing;  on  my  coni- 
paiiion,  who  said  it  uas  not  the  first  time  he  had 
seen  such  a  thinjr,  lashed  it  vigorously  with  his  whip 
lur  some  moments,  hut  without  producing  the  sliglit- 
e-^t  ehect." 

Mr.  Nfor^Mii  in  his  hook  on  the  heaver  gives  the 
following  instance  on  what  he  assures  us  is  excellent 
authority:  ".\  fox  one  night  entered  the  he.i-h.use 
of  a  farmer,  ami  after  destroying  a  large  number  of 
fowls,  gorged  himself  to  such  repletion  that  he  could  ' 
not  pass  out  through  the  small  aperture  by  which 
he  had  entered.      i  he  proprietor  fouiui  him  in  the 

iiorning  sprawled  out  ujion  the  floor  ap[>arently  tiead 
from  surfeit;  and  taking  him  up  by  the  legs  carried 
him  out  unsuspectingly,  and  for  some  distance  to  • 
the  side  of  his  house,  where  he  dropped  liim  upon 
the  grass.  No  sooner  did  Keynard  find  himself  free 
than  he  sprang  to  his  t'eet  and  made  his  escape." 
Dogs  are  freijuently  (.iecelved  by  this  ruse  of  the 
fox  and  doubtless  foxes  have  many  times  owed  their 


•itS 


.S//////(>   ///   .hi'iDiiil   liili.iiinr 


llM'S  to  Its  .lid.  It  li.ls  luill  olicri  iiutiml  til, it  It 
oiir  u  iliiiiiMw  s  Iriiiii  .1  |,,\  \\  In.  n  li  js,  t'ci^nin^  it  ina\ 
lie  sciii  tu  sl.'uK  njuii  its  eyes,  tlun  r.iisc  its  lu-.ui 
aiui  i.irchilK  In.ik  .iiimhuI  to  sci-  it  its  iDcs  are  at 
a  sate  liistaiKe,   aiui   tm.ilK    si.nnpcr  ott. 

While  in   inseas  the  iiistiiut   n\    t'eiy;iiin^'  de.nh   is 
proh.ihK    .1   siinple    retlex    ie.ut:iui    to   oiiter   stiiiuih, 
jit  is  ijouhtless  .issiiu.ueil  in  hirvis  .uul  espeualU  ni.iin- 
'111. lis  uith  a  tiller. iMv  .uute  eonseiiuisness  ot  fh^'  situ- 
i'tiiiii.      It   involves  a   more  or   less  ileliher.ite   inten- 
tion to  proht  hv   the  ileieptioM,  vet  .it  the  s.mie  time 
it    is   [irohahlv    not    .1    result    ot    lonsiious    relleitioii. 
I  he  iiistina  IS  there,  or  else  sinli  .1  nniise  ol   action 
udiiM    not    oeuir    to    tlu'    .inim.il's    miiul.       Were    it 
•  itheivvise  it  vvoiiKI  he  ditiieult  to  umlerst.inJ  vvh\  the 
ruse  is  adopted  oid\    in    certain  speues   while   m.iny 
others,    ei|u.illy    intelligent   and    tOr   whom    it   would 
he  an  c(jually  adv  anta^'eous  strat.i;,fem,  never  mani- 
fest it.       I  here  uiii  he  little  douht  tliat   ,1   tOx  whieh 
slowly  o[iens  its  e\e  .iiul  w.irilv   looks  around  is  aet- 
j  in^  with   .111  intelligent   .ippreuation  ot'  his  prcdiea- 
'  mcnt,  hut  it  is  not  to  he  interred  that  he  eould  have 
reasoned  out  his  eoiirse  ol   action  did  not  an  innate 
nroelivity   in   that  direction    t(Uin   a    part    ol    his   iii- 
stiiKtiv  e  m.ike-up. 

I  he  physiological  cotidition  in  wh.it  is  called 
death-tei^iiin^  is  iiuite  diltereiit  in  dilterent  tOrms. 
W  hile  there  is  a  teener. il  rel,i\ation  ot  the  imiscu- 
latiirc  in  the  sh.im  death  of  some  ol'  the  hirds  and 
mammals,   the    teiiit    in   most   ol    the   lower   animals 


l>ll    -J  O  I   I    KJ  ^    ^J  JO.  v/l  V-I.&.0 -1^^ 


I'll,     hi'liih  I    •'/    /■■  I, mill. I    l>'  iith 


\\  I  h.ir.ii  til  i/fil  In   a  tct.iiiu    uinti  ,i>  ticii  i>t   tlu   imis- 

vUs,  llu-     .IttitUiirs     .l>su!IK»!    In     Ill.lIU      tntllls.     Mll.ll 

as  rulliny;  iiitu  a  b.ill,  kn  pini,'  tlu  Kun  ami  .ithcr 
appcihia^'is  lirawii  Jnsi-  {,.  thr  I'niU,  nr,  in  snmc 
lasL-'H.  linMlti^'  tluiii  stiMiL^lit  aihl  ri^^i'i.  an-  mkIi  as 
can  be  maiiitaiMiii  d'tU  at  tlii  oist  «>t  consiiKraMi- 
inuMiilai-  iftdit.  It  a  Kanatra  is  piikiJ  up  In  one 
(it  its  slfiulir  Kj^s  it  ina\  be  luKl  mit  lntii/i'tUally 
t'lir  a  icinsiileraMc  time  uithdiit  eaiisin^  the  ie^  to 
beiul.  I  he  situation  is  similar  to  that  of  a  man  . 
sei/.eil  below  tlie  knee  ami  lieKi  out  straight,  fate 
upwarJ.  without  eausin^^  the  knee  to  beiul.  As  the 
ie^rs  of  Kanatra  are  relatively  e\eceJin^;!\  slemler, 
the  museular  tmsidii  whieh  the  insect  maintains  must 
be  intense.  Similar  musuilar  rii^iility  is  shown  in 
the  waikini^-stitk  C'arausius  studieii  by  Sehmidt. 
S|>ecimens  ^upportevl  In  the  rip  of  the  abvionien  ami 
the  ends  of  the  (^itstiv  t JkhI  fore  ie^^s  wouKI  lie 
straight  as  a   stiek   lor  hours. 

Death  fei^nin^  is  ii.arkeilly  intluefueJ  by  external 
conditions  such  as  li^dit,  contact,  tnoisture  ami  espe- 
cially temperature.  In  experimentin^r  with  amphi- 
poils  I  ha\e  found  that  when  the  temiv.Tature  is 
lowered  the  lieath  feint  persists  tor  a  considerably 
lonjfcr  time.  The  same  is  strikitij^ly  true  of  the 
ticath  feint  of  Kanatra.  At  temperatures  hitrher  than 
the  normal  the  Se\erins  found  that  the  duration  of 
the  death  feint  in  the  water  bu^s  Nepa  and  Helos- 
toma  was  u;reatly  decreased.  .\  sudden  transition 
from  a  warm  to  a  cold  temperature,  liuwe\er,  was 


I  <l 


Stii(li(.^    in   .hiniidl   lUJutiior 


touml  ri)  ilitiiinlsh  the  tiuratidii  of  tlu'  t'Jiit  in  hotli 
of  tliLsc  spcelcs,  owinj^r  po^siMy  to  the  shock  effect 
{)t    the  siuicieii  ehim^e. 

I  he  iiiflueiue  of  !i^ht  mi  tile  tluratioii  of  the  feint 
has  been  stinheil  liy  the  .Se\erins  in  tlie  forms  just 
iJK-ntioiiecl  ami  liy  myself  in  the  water  hii^i;  Hanatra. 
1  lie  results  a^rfcc  in  shouinj^  that  the  duration  of 
the  leint  is  greater  in  liim  than  in  stroni,^  li^ht,  and 
that  the  leint  is  further  shortened  if  a  lit,rht  is  ke[)t 
ino\inf,r  ,)\cr  the  insect.  Ihe  latter  result,  like  the 
former,  is  prohahly  due  to  the  ,ij;reater  stimulation 
to  which  the  f.'iKniiuK  Insect  is  subjected.  As  all 
these  water  huj^s  are  positisely  phototaetic,  li^ht 
tends  to  elicit  an  acti\e  response  uliich  antagonizes 
the  iiiitinet  of  fei^niiiir  death,  in  a  Ranatra  which 
is  iniluced  to  come  out  of  the  death  feiiu  hv  moving 
a  li<,dit  alio\e  it,  the  tirst  sij^nis  of  life  manifested 
are  orientin.u;  mo\  ements  of  the  head  which  take 
place  in  pertect  unison  with  the  mo\  ements  of  the 
lijjjht.  I  hese  are  tollowed  hy  swaxinir  movements 
of  the  hotly,  until  linally  tiu'  insect  attempts  to  follow 
the  light  hy  walkinjj;  or,  if  hi^^iK  excited,  hy  Hyinj^r. 
It  is  a  curious  f.ict  that  while  the  water  hugs, 
Nepa,  Melostoma  and  KaiKitra,  feigi^.  death  very 
readily  when  our  of  the  water,  they  will  do  so  nuich 
less  readily  wluii  sul)meised  in  their  natural  ele- 
ment. In  Ranatra  repeated  manipulations  under 
the  water  usually  fail  to  eli.it  aiutliing  hut  a  mo- 
mentary ,ind  undecided  respoi.se.  Nepa  i.nder  the 
same  circumst.mces    feigns    for    a   sonicwh.u    lc;,iger 


■  I     JO!   I    \^  JL.    ^J_lJ.v^t^_J-L^J_JVJ 


The   Iii.-liiht   of   l-'ih/nliii/    Dralli 


2  I  I 


time,  ;uul  Bcld^ti'ina,  in  L\^cptii)iial  cases,  mav  tci^u 
1(11-  a-  much   as  a    t\u    mimitLS.       Ihrnwrnti  any  ot 
tlu'sc  msctts  iiitii  watLi-  whiK'  the)    arc  Ici^niin^r  usu- 
ally terminates  ihe  I'eint   at  oiue  (ir  in  a  short  time. 
The    transiti(.n    Irr.'n    air    to    water,    e\en    when    no 
tem}-erature    chan^^es    are    cneuuntercd,    proilnccs    a 
marked  etieet  on  the  reactions  ot'  many  semi-aijuatic 
forms.      In    Kanatra    and  certam   terrestrial    amphi- 
pods,  as  we  have  seen  in  a  prexious  chapter,  it  pro- 
duces a  sudden  reversal  of  phototaxis.  a  chancre  not 
improhablv  due  to  trie  inlluence  ot    contact  stimuli. 
it  IS  not  improh.ible  that  it  is  the  intluence  of  con- 
tact   stimulation   th.it   terminates   the   ,1  Mth    teint   ot 
a(iuatic   !niii;s    when    thc\    are    pl.iced    in    the    water. 
Most  insects  and  crustaceans  which  fei^n  can  be 
caused  to  ,h)  so  re(>eatedl\   by  stroking  or  handlm^r 
them    as    soon    as    they    show    signs    of    activity.      1 
have  performed  a  number  of  experiments  on  amphi- 
pods.    I'.anatra,  beetles  and  or!i-wea\  ing  spiders  to 
ascertain  how  long  the  lieatli  feint  may  be  continued, 
and  to  determine  also  the  lengths  of  successive  feints. 
In  all  the  forms  experimented  with  there  was  tound 
to  be  much  xariabiliiy  in   the  behavior  of  dilterent 
individuals,    so    that    it    was    necessarv    to    pertorm 
numerous   experiments   in   order   to   arrive    at   trust- 
w.n-thy  ciuiusions.      In  general,  all  the  forms  stud- 
ied showed  a  gradual  diminution  in  the  iluration  ot 
successive    feints,    until,    often    after    several    hours, 
it    was    no    longer    possible    to    evoke    tfie    response. 
Similar  experiments  undertaken  .it  my  request  bv  the 


2  I  2 


Sludit->   ill   ./iiitrici!   fulidiinr 


Scvcnns  sIkiucJ  the  sanu  pliciiouu  nuii  in  Ncpa  aiui 
ik-Iostonia.  I  alirc  in  his  stuJics  on  Staritcs  I'ou  1 
;in  increase  in  the  Juration  of  t!ie  lirst  ii\e  feints,  hut 
his  ohscr\ations  were  not  sii;:'eientl\  nunicrous  to 
eliminate  the  rather  hir^e  ainount  of  \ariahiht\  ilue 
to  unknown  causes. 

As  tile  teinrs  yrow  slioi'ter  the  attitudes  of  the 
or^Mnisni  hei.oine  less  characteristic.  Aniphipods 
ami  [)ill-hu^rs  ij,,  n,,t  roll  u[i  so  u.nip.letely  or  keep 
the  appeniia^as  (h-aun  so  Joselv  to  the  hojy.  Spi- 
«lers  ami  heetles  do  not  assume  so  conipact  a  !orm. 
and  in  <,rener:!!  it  ma\  lu'  said  that  the  muscular  svs- 
tcm  ^i\es  evidence  ot  diminislicu  contraction.  As 
tile  death  teint  is  usual!)  accompanied  h\-  a  tetanic 
contraction  o|  tlie  muscles  one  would  expect  to  lind 
a  diminution  in  the  duration  and  perfection  of  the 
response  as  a  simple  consequence  of  fatitrue.  In  a 
sniiilar  niamter  the  diiTiinution  of  the  duration  of 
the  teint  that  ociurs  under  hi,L!;her  tem[)erature  may 
he  due  to  the  faa  that  the  muscles  heo-me  exhausted 
more  lur  kl\  when  the  inetaholism  is  increaseii  l)v 
the  liii^her  te!n(ierature  of  the  hody. 

I  he  experiments  inidertaken  to  ascertain  what 
part  ot  the  ner\ous  s\>:em  is  mo^t  concerned  in  the 
death  Icint  have  vicjded  sonuuhat  varied  results. 
Rohertson  tound  that  in  the  active  specie>  of  s{>iders 
i-.})eira  and  Amaurohius  the  siiam  death  reaction  oi^-r- 
sisted  atter  tile  remov  d  of  the  iMMin,  and  was  niani- 
lc>ted  ill  a  vve.ikened  lorm  when  th.-  suheso[iha^eaI 
i,Mni,rli,,n   and   even   the   first   thorauc   were   removed 


lYt      _IOI     I      \^ -L.     \^  ^  J^  \J  t  *^  JL.  ^^  -i  %^ 


riii-    hi^liihl    <ij   I'cujuiiuj    Diiith  213 

;iK..,     In  a  slii^ixi'-Ii  ^pi.Kr  Ccl.rnia  Knhortsnn  t'nund 
that    "TIk-   sham    death    pn^turc   (.aniutt   he    irnkiccd 
without    the   head   ^aii-ha."      Schmidt    finds   that   in 
Carausiiis  the  dea'-h    feint   entirely   disappears   aft-.-r 
the  renicx  al  of  tlie  hrain.      My  own  experiments  on 
Kan;;ira    showed  th,a    r:';no\al   of  the   brain    caused 
a    marked  iliminution   in   the   duration   ol    die    teint, 
alfhouij;h   the   resj-.oMsi;   eouKl   still  he  induecii  in   de- 
cerebrate speumens.      If  a  fei^ninir  individual  bo  cut 
in  two  across  the  prothorax  the  posterior  part  olten 
continues   to    retain    its    ritj;idity    tor   sduie   time    and 
mav  be  thrown  l^ack  into  the  death   feint  a^ain  if  it 
is  picked  up  a-      stroked.      Similar  results  were  ob- 
tained in  Belo.>Loma  and  Nepa  In  the  Se\crins,  who 
ha\e  investigated  the  roK   of  the  nervous  system  in 
especial  iletail.       I'he  cataplectic  state  which    Prcyer 
and  \"erworn  found  couKl  be  imluced  in  decerebrate 
fowl  may  be  allied  to  the  conditions  described  above. 

(  )ne   marked    cha.racteristic   of   the   death    teint  is-' 

an  apparent  insensibility  to  pain.     De  deer  in  writinj^  ' 

of  a  borinii  beetle  .hi">'!:im  pnliihix  savs  that  "you 

may   maim   them,   pull    them   limb    from   limb,    roast 

them   o\er   a    sh.w   !'re,   luit    \i>u   will   not   ^ain   your 

L-n^:  not   a   joint  will   ihev   move,    nor  show   by   the 

least    symptom    that    thev    suffer    pain.       A    smiilar 

apathy  is  shown  bv  some  species  of    saw-flies    {  Ser- 

rifera),  vvhi-.h  uhen   alarmed  conceal  their  antenna,^ 

under   their   bodv.   place    their   le^rs   close   to   it.    and 

remain    without    motion    even    when    transfixed   by    a 

pin.     Spiders  also  simulate  death  by  folding  up  their 


214 


Sliidi,.    in   .hihiuil    lirlhiiinr 


It'K'V  l.iliin.ur  fn„„  thrir  staticn.  :.iui  r.  :n;ni,iii^  ni..- 
tinnlcss;  and  u  lun  In  this  situation  niav  he  puTccd 
;m(l  torn  t..  pircrs  uith.-nt  th.ir  r\lilhitin,<,r  th.'  sHi^rht- 
c-st  svniptnn,  mC  ,,;iin."  I  lie  Sr\  rrins  trirJ  tfU'  ap- 
pIicatH.n  (.f  heat  to  Hclnstnn)a.  hut  the  insrci  was 
iinarlalily  iM-.-u^rht  ,,ut  of  its  tcint  an. I  made  strui;- 
kIc's  toesuipe.  alfhou.uh  it  nn.i^ht  enchire  n)ore  or  le'.s 
nuitihition  without  inakinj^r  ;„u  re,pon^e.  I  ha\e 
'"unci  that  a  fei-nin-  R;,naira  "will  allow  iis  le-s  to 
he  snijiped  oft  without  hetrayin-  the  least  ,no\  e- 
inent  heyonii  an  oeeasional  twitJi.  Similar  inscn- 
^ihility  has  heen  ohserve.l  in  \epa  (  Severin  ) .  Carau- 
•sius    (SchniiJt)    ami  other   forms. 

As    has    heui    pointed    oiit    h\    Romanes,    I'rever, 
\crworn,   Sehmidt   ami  others,   the  in^tinet  of   fcii^ii- 
■  in^  death   is   douhtless   Joselv   eonneeted   with   mueh 
;«'(   what  has  heen  ealled  hvpnotism  in  the  lower  ani- 
mals.    Craylishes.   fn.j^rs.  li/ards.  eertaln  snakes  and 
many   hirds    and    mammals,    may    hv    a    \er\    simple 
pr()cess   he   thrown    ifito   an    inaetive   condition    froir, 
uhieh  thev  are  not  readilv  aroused  l.\   external  stim- 
nh-_    In  ordinary  death  fei^rnin.ir  the  animal  falls  into 
Its  immohile  >tate  upon  sliL^^hi  pro\  .,eati..ii ;  a  toiieh. 
or  even  a  jar  is  sometimes  all  that  is  re.juired.      In 
the  so-called  eases  of  hypnosis  more  or  less  manipu- 
lation is  necessarv.     The  excitin-  cause  in  hoth  cases 
IS  ^enerallv  sonie   form  of  .ontact  stimulus.      In  the 
lupnotism  of  anim.ds.  as  \'er\\orn  a;i  1  others  ha\e 
shown,    there    is    diminished    retle\    irrjtahilitv,    a'ld 
usually    tonic    contraction    of   many    at    le.ist    of    the 


i«i   joi  I   \^-i.  *u-ja.V''icja.vj^«»« 


'/'//,     lii^lniil    <>j   h'lUjunti/    l),ath  21^ 


inu'cliv  Similar  plu'iioim'tia  arc  ohscrvid  in  the 
ilcath  tcii^nin^  ^^i  iiiaii\  tOrins,  >;.mic  "i  tlu-  insects, 
as  \vc  lia\c  seen,  slw.winii;  a  huk  .«t  .  espnnsl\  cncss 
tliat  is  triiK   rcntarkaMe. 

The   iiulepciulciit   <le\cl.ii>inait    n\    lieath    fei^niint,' 
alonir  inativ  diHer.iit  lines  ot'  ilcs.  cut  makes  it  pr«>h- 
;-hle  that  we  must  hxik  f.ir  the  oriiiin  o\  this  eurious 
instinct  in  seme   t'unJamental   and   uMespread  mi)>ie 
i.t   helia\i<.r.      In  a  paper  on  the  u.  ath  feiK^iini,'  ot 
terrestrial  ampliipo'is  th.e  writer  has  su^^^ested  that 
the    ileath-t'ei^mintr    instinct    in    these    forms    hail    its 
origin    in    an    accentuation    of    the    thi^iTir)taetie    re-  , 
sponsc  which  is  such   a   prevalent  trait  of  oehaxior 
anion^r  the  amphipods  in  general.     It  was  fouiui  pos- 
'■  to  establish  a  series  of  stages  between  the  tv[)- 
.i.    deatli    feint   of   the   !ari,re   terrestrial    amphipod 
■I'alorchestia  and  the  (-rdinarv  thiijmotactic  reactions 
of  the  a(]uatic  relatix  es  of  this  species.      In  Or,  /;,>7n/ 
p,ilii^tri>,    a   species   not    so   c\clusi\elv   terrestrial   as 
the  preceainir.  the  h.uK  du  'in^  the  death  feint  is  less 
clos.lv  curled  up.  the  aiipenda-es  are  n<it  so  closely 
drawn   uji  to   the   hod\,   and  the    feint  is  not  so   per- 
sistent.     In    tlic   small    Or, /;,.>/;<;   <hyi!is,   which   lives 
usually  ;iear  the  water  line,  the  death  feint  is  shown 
i„   a   somewhat  less  decided.   w,t\.   while   am.    il,^  the 
aquatic  members  of  the  Orchestiida'   the   same  trait 
is  manifested  In    a  tendeiu\   t..  curl  up  and  lie  »luict 
when  in  contact  with  i-,>ik-  or  -eaweed.      i  o  one  who 
has  studied  and  o-mpared  the  attitudes  and  behavior 
(.f  this  serie-  of  forms  there  can  be  little  doulu  that 
the  typical  death  feint  of  the  must  terrestrial  of  the 


2l6 


Sl/idirs   in   .hi'utuil   Hrlunior 


-spL'cifs  has  it^  iKisis  in  the  tlii.^motaxis  of  the  afjuatic 
roniis.      As  the  species  studieii  become  more  terres- 
trial   In    hahit,    the    thifrn)()taxis    becomes   gradually 
specialized  into  a  tvpical  instinct  of  feijrnin^r  tk-ath. 
Manv  tacts  indicate  that  death  feiirninfr  in  insects 
:ind   other    forms    has    had    a    simihir   origin    in    the 
tliiRmotactic  response.      It  is  a   rather  strikin^r  fact 
tliat.    with    \er\     rare    evceptions.    it    reijiiires    some 
jtorm  of  contact  sti-     ilus.  it  may  be  Init  a  touch,  jar, 
jor  e\  en  a  breatli  ot  air.  to  elicit  this  instinct.     One 
"I    tlic   \cr\    few   exceptions  to  this   rule    which   has 
been  recorde.l  is  attorded  by  C'arausius,  whose  death 
femt.    accordinir    to    Schmidt,    arises    from    internal 
causes,   and  can.Ktt  be   iiuhued  by  anv  discoverable 
environmental  a.uencv.     .S!i,.u!d  it'be  definitely  estab- 
Iislied  tliat  this  case  is  trulv  one  of  "autocatalepsy," 
as   it  has   Iven   called   bv  Schmiijt,    it   would   not  be 
latal  to  the  supposition  that  it  beiran  orijrinally  as  a 
reaction  to  contact:  iov  ir  is  not  without:  precedent 
tliat   an  instinct  ha\  ini;  originated  with  reference  to 
one  leature  of  the  environment  should  finally  come 
to  be  set  into  o[icration  bv  a  i]uite  different  cause. 

I  hose  cases  ,.t  death  feij,niin^r  in  which  there  is  a 
limp  and  relaxed  condition  of  the  musculature,  such 
as()ccurs  in  some  birds  and  mamnuds.  may  have  an 
orii^rin  ijuite  different  from  that  of  the  more  preva- 
lent cataleptic  type.  The  suji^cstion  that  death- 
cii^miiiL^r  had  ts  .M-iijiti  in  the  partial  jiaralysis  pro- 
by  fear  mav  perha[)s  a[)|ily  to  cases  such  as 
altho'i,ij;h  this  expl.mation  cannot.   I   feel  sure, 


clucec 
these 


1^1     _J  O  I    ■ 


References 


217 


be  cxtcmk-a  to  the  derivation  ..1  the  tvpical  tonn  of 
this  instinct.  While  there  is  siinuhition  ot^  de.ith  1:1 
hoth  types  of  hehaxior  we  have  aescrihed,  it  is  prob- 
able that  we  have  to  do  with  two  distinct  kinds  ol 
reaction  diftcrin^r  both  in  their  physioh'^Mcal  charac- 
ter and  in  their  phylctic  origin. 


Ria  IKINCIS 


Dakwin,    C.      Chapter    on    instiiut    appended    to 
KoiiKines'  mental  evolution  in  animals.      "^^4-^ 
F.\I5KI.,    ].   H.      Souvenirs  entoniologiques,    I.    7. 
IIol.Ml.s",  S.  J.      (  1  )    Death  feii^niin^  in  terrestrial 

aniphipoeis.     Biol.  Bull.  4-   ";» '  -   "r ',v 

(2)  Death  fcifining  in  Ranatra.     Jour.  C'onip. 

Neur.  Psych.   15,  2'>o,   19(^6. 

(3)  The  instinct  of  feigning  death.     Pop.  Sci. 

Mon.  72,  179,  i<r*^- 
HlDsoN,  \V.  H.      Ihc  nauiralist  on  the  I, a  Plata. 

1892. 

KiRliV,  W    and  Sl'l  Ni  1..  W.     .\n  introduction  to 

entomology.      ^>th   ed.,    1  S4''j. 

IjMIM.K.  p.  Pntersuchungeii  ubcr  ilcii  sogui- 
annten  d'otstellredex  der   Arthropo.Kn.      />it    nllg. 

Phvsiol.   16,  373,    19 '4- 

NIoK(;.\N,  L.  H.  I  he  \merican  beaver  and  his 
works,   I'hila.  and  PoiuI.m.   iShS. 

Pol.IMAM  1,  <).  Studi  di  I  i^iolo^ia  etoloiri^a.  IK 
Lo  stato  di  immobilita  tcinpoi-anca    i"niurte  appar- 


2i8  .S'///,//Vv   in   J„l)!ni!   n,li,rJur 

^■nU-''.'-lnUn,tv\\nr)  -..i  Cr.,st;uci  I5r:uhinri. 
/•-■ir.    ;i1|m;.    r||\si,,l,     1^,    2.. I.    1,^,2. 

H<M'.iK,soN,  T.  H.  ()„  ,1,,.  ••shani-clc.itir  rcll.A 
"1  ^I'ulcrs.     j,,ur.    I'luslol.    ^i.  4,,,.    ,,^,,4. 

'<"MAMS   j.   (..      M,,u,l    ,,,.U,ti„n    in    animals 

^'  vikis,  II.  II.  j...  ;,„j  .s,  \,Ki\.  II.  C-.  \n  cv 
I'cnmcntal  stu.lv  o„  tlu'  >i.ath-t\iirnin;;  ..t  Hdnstn-na 
(■/.-ntha  auat.)  Ilunilnnim  Sav  ami  Ncpa  apiail  11a 
I   lilcr.     Hilia\i(,r  .^^.^..^raj'il^,  \',,1.  |,  \,,    ,     ,  ,^  ,  , 

SdiM,,,,.  I'.  Katai.psic  .in-  I'liasnii.luu '  Hiui' 
^  '■■'If-  ,^."i.   i'>.^    i'>  1.^ 

VlKWoKN.    M.       (,  )     Tonisdu'    Rcflcxc.       Arch. 

(2)  HeitniKc  /ur  I'lusi..I..i;ic  dcs  /ciuralncr- 
vir.systcrns.  I  |\;i.  Di,.  soircnanntc 
I  lypiK.sc  Jcr    f  lire.  Jona.  1  S(yS. 


Ill    -ivJi   I    ^^a.   vj_lj.>_/n_jj.,_»_iv^ 


XII 


I  III 


Kl  (  (i(.\|l  |i)\     1)1      SlA 


H 


(  )\V    .jo   the    m.ilcs   of    ttu'    lower    ;mimals    dis- 
tin^aiisli  tliL-   krnalcs  of   their  ouii  spicies  troiii 
all  the  rest  of  the    iniiiiate  creation?     Ohvioiisly  the 
pcr(K'tuatio!i    ot    the    race    ilepcmls    on    the    circum- 
stance that  the  male  is  correctly  ^nrulcil  in  the  choice 
of  a  mate.     A  male  beetle  or  hii^  will  pass  hv  with 
indiHerence  thousamls  of  otfier  varieties  of  insects. 
Init  in  the  presence  of  a  female  of  his  own  kind  his 
interest  is  keenlv  aroused.      It  almost  ^()es  without 
sayinjz  that  this  jiower  of  discrimination  is  a  matter 
of  instinct.     It  is  easilv  demonstralile  in  most  animals 
that  the  element  of  experience  is  entirely  unnecessary 
for  the  proper  solution  of  this  important  problem. 
Apparently  the  male  is  ^niided  by  a  S(U-t  of  elective 
affinity  to  tlu  rii^ht  object  upon  which  to  bestow  his 
attentions.     What  are  the  sijrns  by  which  this  oliject 
is   reco^m/ed  .' 

An  important  factor  in  the  discrimination  of  sex 
that  naturallv  ot^cur^  to  one  is  the  sense  of  smell. 
The  lower  animals,  or  at  least  manv  of  them,  are 
intluenced  bv  odors  to  an  extent  which  we  with  our 
comparati\  elv  obtuse  olfactories  lind  it  difficult  to 
appreciate.      The  odors  of  most  species  arc  specilic, 


Sliiiiifs    in   .fii/>n,i/   liihiiiKir 


•'"''  '^'"  i",|i\l,iu.ils,  ;„  lil^^rfuT  f,,ri„s  ;it  least,  have 
■I'l  n.l.M-  iuailiaiK   thur  nun  uliicli  a  I'lr.,u||i,,i,n(l  is 

■if'K'     tu    .lisrld^ruisll     hnni     aillMM^r    ,|,./l'ns    of    ..thcTs. 

Di'tciHMus  in  (ulur  hcjucntlv  i  liai.ii  tiri/c  tlu'  two 
MNcs.  aiul  lu-mv  attnrj  .,  tVasIMc  means  ..f  sex  dis- 
i' n  m  i  n  a  f  i  1 1 1 1 . 

I  lir  males  .,1  many  lOrms  |ia\e  muih  mere  lii^^hly 
iI^m!m1u,|  ,.l|-,ut(.ry  crLjans  tlian  the  females.  Ihc 
.mtenna'  ,.1  inseets  uhich  eont ain  the  olfaetury  ..cnse 
<'r-ans  are  fre.|uen;l\  larj^er  an. I  m,.re  e.-mplex  in 
till-  males.  In  the  drone  hee,  h.r  iiistanee.  the  ..Ifae- 
^*n-\  pits  ,.f  tlu  antenna-  are  man\  times  more  iiumer- 
<His  than  in  the  .jueen  or  worker.  Many  male  moths 
li.Me  I.irue  leathered  antenna',  whereas  these  organs 
:"-^-  "Huh  smaller  in  the  females.  It  is  mainly 
tliniUKh  the  sense  ..f  smJI  that  the  male  moths  are 
ahlc  to  hnd  their  mates,  and  in  s.Mue  speeics  this 
sense  IS  deNeh.ped  to  a  de>,rree  th.it  almost  surpasses 
I  I'edenee. 


n  one  of    Ins  most   c 


natur.ilist 


i<-li.i,ditful  essays  the  I'reneh 
al>rc  tells  of  the  nuptial  tliL,rht  of  the 
"lales  ot  the  lar-e  and  heautifulK  eoh.red  moth 
called  the  great  peaeoek  (  !,■  ,,rand  pan,,).  \  cocoon 
uhieh  was  kept  in  I  ahre's  study  had  produced  a 
tnnale  nrnth  uhieh  was  placed  under  a  gau/e  cover 
In  the  evening  the  observer  had  his  attention  at- 
tracted by  the  call  of  his  young  son  :  "  'C<.me  (juick 
cnine  and  see  these  hutterllies .'  Big  as  birds !  The 
n-om  !s  full  of  them."  Several  of  the  large  moths 
had  come  into  the  room  through  the  open  window 


Tilt    Rit  i),/iiili<iii   of  Stw 


221 


Others  had  cntorecl  the  kitchen,  .iini  still  others  were 
found  in  \  .irioiis  rooms  \vhere\er  tlieie  was  a  ehaiue 
for  them  to  enter.   .   .    . 

"It   was   a    memorable   nii^ht — the    Mi^ht    ot    the 
(ireat  I'eaeoek!     Come  from  all  points  ol  the  com- 
pass, warned  1  know  not  how.  here  were  torts  lo\ers 
eajjcr   to   ilo    homai^e    to    the    maiiien    princess   that 
morning  horn  in  the  sacred  precincts  ol  my  study. 
i'he  ni^ht  was  one  of  black  darkness,  yet  the  moths 
threaded   their   way   through   the    trees   surroiindinL^ 
the    house,    and    lame    through    opm    windows    into 
darkened   rooms   without   a^radi^^   iti   tiie   le.ist    the 
scaly  cos  erin^  of  their  win^s.     But  keen  as  the  sense 
of  sijrht  in  these  insects  may  be  it  is  not  throu^h  this 
sense  thai  the  males  are  ilrawii  tow.ird  their  intended 
mates.     "When,"  sa\s  I  abre,  "1  placed  the  females 
in  boxes  whieii  were  imperfectK  closed,  or  which  ii.id 
chinks  in  their  sides,  or  e\  en  had  them  in  a  dr.iwer  or 
a  cupboard,  1  found  the  males  arrived  in  numbers  as 
jrreat  as  when  the  object  of  their  search  lay  in  the 
cajfe  of  open  work  freely  exposed  on  a  table.     1  ha\e 
a  visiil  memory  ni  one  esenin^;  when  the  recluse  was 
hidden  in  a  h.it-box  at  the  bottom  of  a  wall-cupboard. 
The  arrivals  went  straight  to  the  closed  tloors,  and 
beat  them  with  their  winjj;s,  t<u-tin-,  trying  to  enter. 
Wandering  pilgrims,  come  I  know  not  where,  across 
fields  and  meadows,  they  knew  perfectly  uliat  was 
behiml  the  do(jrs  of  the  cupboard." 

I'abre  cut  oH  the  antemia-  ot  several  ot  the  males 
of  this   and  other  species  of  moths  and  touiul  that 


'•^-  S///./;;  -    ///    .liiiiiuil    /I,  lijunr 

''."'>    ''"'^'I  f"  .i|'|M..,i.li   the    \lunlt\    ,.|    iIk-    knialv 

Hu'  |.rc-v,ur  ul   uti.cr  .u|u,s,  uhul,   svnulJ  make  an 

•'iniost   intnkral.k    st.uli   ni  ..ur  .  .u  n  mo.i,:!..   l.iiloi 

t'-   ^l^trr   rlu'   >„aks   i„    the    K,,s,    tnun   tlu-   ohjca    ..f 

tMnrs.arJi.     Mu-  .u|n,-.  ac  u.nlin-  in  I  ahrr,  sccmk-.I 

'"    I'c    carruJ    aKMinsf    uiirLfits   uf'    air,    t..r    a    rare 

(u..aKs,uu...uiMMlu    I  cs>u-  iVauKk  Jrcu   ,nn,ur- 

"us  Mialcs  ulncl,   Iku    :u,l,  ///,    ;.,,„/  t,,  ,!„  ,,!,„.  ..( 

IKT  cnnlu.u.uni.      It    ,s   ^.arc.K    t,,   lu-    u..,ukrcj   at 

iMat   I  ahrc  omsJcKreJ   tlic  suis.    -.1   m.kII   t..  .Icpcul 

"•  I'-"'  «'"  "thcr  nuans  than  thr  ualtlnunf  oJ,,r..(is 

[••"■tulcs.  a  s.Mt  .,t   lor.,   a.  tiny  a  t  u  r  th.   niann.r  uf 

>-a\s  ut   h.uht  ur   X-ravs  a,)J  uipai-k    nf   raJiatmy  to 

;i   ^rc.it   chstan.c  Jrvpitc  a.Krrsc  anruus  of    air. 

Hif    rok-   of  Mnrll    in    sex    ri-.oy„ition    ainony   th.- 
trustaicans  is  niorc  uncertain.      The  antennal   sense 
«n-uansuhuhare  ,erv   prol-ahly  ..Ifaetorv  „,  funetion 
are    m    s.une    speeies   nuuh    Letter   Jevelope.l    in    the 
"•ale  sex.      Hut  httk^  is  kn,.un.  hou.ver,  in  regard  to 
tlic   means   l.y    uhieh    most   speeies   t,nj   their   mates 
In  s..me  amphipoj  erustaeeans  with  whij,  the  uriter 
cxperimente.l  a  teu   \ears  a^o  oltaaorv  stimuli  uere 
'"^'"^1  t"  I'lay  httk'  or  no  part  in  the  diserimination 
of    sex.       I  he   maks   ot    tins  ^mu^^  lia.e   the   eurious 
hahit  ot  .arrMMi;  the   females  about  under  the  bo.K. 
I  his  aet  ol  transp.,rtati..n  has  no  Jirea  reference  to 
the   ,mprei,mation  of  the  e,L:u>  fnrth,,-  ,1,.,,,  „.  i„,,,, 
theproxnmty  ot  the  sexe.  uhen  the  proper  tinie  for 
te'-tiii/ation  arrives.       This  oeeurs  soon  .,ftcr  the  fe- 
"lak'  easts  oH  her  skin,  uhen  the  sperms  ar.  .kpos- 


HI     -JOI    I    \_/J.    VJ  _IJ.%_/H_1^.^  _iv 


Till    R(<  "tjniiidii  nf  S,\  21} 

itril  by  the  iiiair  ■)n  tho  \i.ritr;i!  siilr  ot  tlu'  tiinr.ix  ot 
\us  iiKiti.'.  \\tvr  thr  >.'mz>>  ;irj  (crtili/i  vi  ilu'  iii.iK 
(."Diitiriuis  to  swim  ;ibtiut   witli  ihf  tr:ii.il     .is  lictnfi'. 

"1  he  institut  i»t  tht  m  ile  ;iin[>hipiiv|  '  tn  sci/e  atui 
retain  hoKi  ot  the  Icmale  is  one  ot  remarkable 
strcn^^th.  I  he  male  retains  his  hoKi,  dispite  all 
ettorts  to  liislmli^e  him.  with  remarkable  |>erMsteiKe, 
arul  will  still  (.liii)j;  to  tlu-  female  alter  tlu-  i>ONterior 
halt  ot  his  l)(nlv  h.is  been  cut  away.  .My  outi  obscr- 
\  ations  on  the  sexual  beha\ior  ot  amphi[ioils  relate 
mainlv  to  three  species.  .  I i>i f'lulli  ,•  !"ii,/iiiiiniu  Nniith. 
U  Mill  11,1  iltiitdta  Smith,  .iiul  (laiiniiai  ii-  j.im'uiUi^ 
.Sav.  I  he  sexu.il  beh.nior  ol  tluse  thiee  speeies  i> 
remarkablv  similar  although  thev  belong  to  as  manv 
distinct  tamilies.  The  tcm.ile  while  carried  about 
keeps  remarkaliK  im[Kissi\i'.  1  Icr  t'mr.uic  le^s  are 
drawn  u[),  the  abdomen  helw  stronj^ly  liixcd.  the 
whole  bodv  assuming  as  compact  a  lorm  as  posNible. 
She  takes  no  part  in  swimmiiifj;:  the  mo\  ement  ol  the 
pleopods  when  the  body  is  strongly  bent  u[ion  itselt 
Ner\es  only  to  kee(i  a  current  ol  water  pas>iiiir  l,v  the 
j^ills.  She  is  carried  about  like  a  helpli  >s  luirden, 
allowing  her  \  if^orou'-  spouse  to  assume  the  entire 
labor  ot  transportation  and  the  r(.s[)onsibilit\  tor 
keeping;  her  as  well  as  himselt  out  ot  danger. 

"  I  he  ettorts  ot   the  m.de  t<i  sei/^-  the   tern. lie  ,ind 

jret  her  into  the  proper  position   lo  be  carried  have 

the  ettect  ot   iiuluciny;  her  to  throw    hersell    into   tlie 

i(Jii,,|r.l    Hum   an    aniilr    l.\    iln-    uritit    on    '■.-ir\    iviTiiKliitiDli 
ill    Atni)lii|i'M|~."   laiMi^ii-.l   in   ilic    l;i.,l.  .{u.ii    lailKtiii.   \  ■  .1    5.   p. 

J.S'^,      I  ■/D.J 


224 


StUilii's   1)1   .hiiiiid!   Hchintor 


cliaractcri-fii.  bodily  attitinlc  :inJ  nni.iiii  ijuict.     'I'll- 
artltucK'    asMiiiud    hy   the    female    is    similar    to    tha; 
ohscrveJ    in    the   ordinary    thitrmotaetic    reaction    of 
amphipods  ami  may,  perhaps,  be  hut  the  same  form 
ot    response   somewhat  nioililied   ami   speLiali/ed   in 
relation  to  the  funelion  of  reproduetion.     When  the 
.nales   are    torn    a\v;'.y    from   the    females   they   so(»n 
seize  their  partners  a^ain   and  roll  them  aliout  int(» 
■  proper  [losition  and  then  [iroceed  on  their  way  in 
.■('parent    contentment.       The    fetnale,    as    soon    as 
■  --i/cvl  hy  the  male,  curls  up  and  allows  herself  to  he 
rolled  and  tumbled  about  uithoi.t  a   show  of  resist- 
ance or  protest.       1  he  males,   as  a   rule,   are  lar^'er 
than  tlu-  temales  and  usually  j^et  their  partners  into 
the  desired  [losition  (juite  readily:  but  when  a  small 
male  attempts  to  carry  a  l.irue  female  he  expieriences 
much    liitliculty.      I    observed    a    male    1  Ivalella    en- 
ileavorin^  to  carry   a    fem.de   somewliat   lar;j;er  tlian 
himsell.       Alter    sei/iiiLi;   the    female   he    would    turn 
her  around   until   she    fin.dly   c.ime   into    the   proper 
position  lor  transportation,  but  owino;  to  the  I'rjrer 
size  of  his  partner  the  male  could  not  reach  around 
her  boily  so  as  to  carry  her  awa.y.     \o  sooner  was 
the   tem.de  pi'operly  adjusted  than  the  male   would 
lose  hold  of  her  round  bodv  and  the  same  efforts  had 
to   be   repeated.      Duriiijj;   all    this   fierfornumce   the 
female  remained  dutifulK   passive.     After  watching 
the   further  struggles  of  the  male   for  o\er  half  an 
hour  I  became  convinced,  adthough  he  was  not,  that 
he   had  undertaken   an   impossible  task,   and   discon- 


t  ^1     .J  Ol 


Tilt'  Riii>i/)i!ti  'II   (if  Si\ 


22  ■ 


tituK'tl  rin    (i|iscr\  ations." 

That  the  male  a!ii}'hi[Miiis  tin  nut  ilistiii,miisli  the 
t  cm  ales  In'  si.^hr  was  ^hnu  n  1>\  hKuk  milt  uv  er  the  eyes 
(if  several  Jiiales  and  then  phuiti^  them  in  a  dish  with 
temales.  It  was  not  Inn^  luture  each  male  had 
securcil  a  mate.  I  lie  possible  role  of  '.he  sense  of 
smell  was  tesfed  In  remoxin^  from  a  iiuinbcr  of 
males  the  iirst  antenna'  which  contain  the  oltactory 
sense  origans.  After  the  specimens  had  recovered 
I  rom  the  sli^jht  shock  ot  the  ojKratiofi  they  sei/ed 
the  temales  and  carried  tliem  about  in  the  usual  iiuui- 
ucv.  I  hey  reacted  in  tlie  same  way  when  the  second 
antenna"  were   removetl  also. 

In  another  experiment  several  females  were  con- 
tinei.1  within  an  enclosure  ot  wire  ^au/e  which  was 
placed  in  a  dish  of  water  containing  several  ea^er 
males.  I  he  males  paid  not  the  slightest  attention 
to  t!ie  feiiiales  within  the  eniiosure,  but  after  it  vvas 
raised  anil  the  females  allovveil  to  scatter  through 
the  dish,  iiRist  of  the  males  were  toiintl  carrying  their 
mates. 

"If  one  attentively  observes  I  lyalellas  as  they  are 
swimming  about,  it  will  be  seen  that  the  males  tlo  not 
pursue  the  temales,  ;j;reat  as  their  eagerness  may  be 
to  se!/e  and  carrv  mie  ot  the  opposite  sex.  Only 
when  the  two  scxe.>  collide  in  their  a[)[tarentlv  ran- 
dom movements  does  the  male  become  aware  of  the 
presence  ot  the  female.  W  hen  a  male  ami  a  female 
collide,  the  tjjnale  curls  up  and  lies  (juiet  while  the 
male  makes  etiorts  to  sei/e  her.     Shoulei  two  females 


'.ll> 


.^l/itJ.'r.y    ill   .hiniiii!   Hiha\inr 


cs 


(.nllnlc  tlirv  in;i\   uirl   up  t'ur   .1  mmrn'rit,  hut  as  tlicy 
■  irr  imt  sci/nl  ilicv   simui  pass  dii.     Wlicii  two  inal 
iiuct  tlurc-  IS  ottcii  a  li\ilv   M ruiri^'Ic.     I'ach  appar- 
t-Mtlv  attuiijus  t(i  sii/c  auii  (.arry  the  other,  but  as 
nr.ther  will  ^diisLiu  to  rLinaiu  passiNc  they  soon  sep- 
arate.      I  he   dittcrent   reactions  of  the  two  sexes  to 
eoiitait    with   other   inJi\iduaIs   is    the    factor    which 
rtteas  the  union  of  the  males  with  the  feiTiales.     llach 
reacts  to  the  n  laioiis  of  the  other.      i'he  male  has 
a  strong  instinct  t  t  sci/c  and  carrv  other  individuals 
<'t  tile  same  species.      I'he  female  has  the  instinct  to 
he  i|uiet  when  another  ifidi\idual  conies  into  contact 
With  her,  es(>cLi.dlv  if  she  is  seized.     The  instinctive 
reactions  ot    the  two  sexes  are  complementary,  and 
cooperate  to  hrinir  about  :\nd  maintain  the  peculiar 
sexual  association  charaLtei  istic  of  t!ie  (iammaridea. 
"ft   the  association  of  the  sexes  is  brouf^ht  about 
bv  tlulr  peculi.ir  modes  of  reactlt)n  to  certain  contact 
stmiuli,  it  would  seem  probable  that  the  only  reason 
why    males    do    not    carry    other    ma'    >    as    well    as 
females  is  that  the\  are  pre\  ented  from  so  doin^r  by 
the  aal\e  resistance  of  their  intended  mates.     [  was 
a.cordin)j;ly  led  to  rr\    the  exiierinunt:  of  mutilating 
some   male  specimens  so  that  they  could  no  longer 
make  etteuive  resistance  to  seizure.      The  large  sec- 
ond  gnathopods    (the  pHncipal   means  of  defense) 
of  several  males  were  cut  oft  and  the  mutilated  indi- 
viduals   were    placed    in   a    dish    with    several   males 
whieii  were  recently  torn  from  females.      The  muti- 
lated males  were  soon  seized  and  carried  about  as 


til    _ioi   I    v^-l_    Vj     ^  j_  vy  I  vj-1- ^ -»«-- 


Th('   Rri'iipiiiini,   nf  Sr> 


227 


if  they  were  numbers  ef  flie  dtlier  si.x.  In  nne  ease 
a  mutilated  male  was  c:'.  led  about  Inr  <)\er  tive 
h.)urs.  'Ihe  mutilateil  males  were  more  acri\  e  tbau 
feiTiales  are  umler  the  same  contlitions.  ami  ^^^  not 
assume  the  same  bu.iiK'  attitude,  but  nevertheless 
their  captors  carried  them  without  am  mam  test 
awarei^ess  of  the  tleception  to  which  tluv  were  sub- 
jected." 

In  another  p;roup  of  crustaceans,  the  t  ope[ioda, 
the  mating  instincts  ai-e  tiiore  or  k-^s  analoirous  to 
those  of  the  amphipods.  In  the  copepods,  howexer, 
the  males  in  sci/iiiL!;  the  females  iinplov  tin-  tir^t  an- 
tenna-, which  are  often  cid.ir^red  and  esiH'cialh  moti- 
itied  for  this  function.  In  T'v. /"/>.»  inuhr'uilic^,  whose 
heha\ior  was  studieil  by  the  writer,  the  male  clasps 
the  female  iust  in  fripiit  of  an  entarifcment  at  the 
base  of  the  abdomen.  M.des  show  im.Ji  eai^erness 
in  ^rasiiin^  the  females,  and  they  ma\  be  poked 
about  rouL^dilv  with  a  needle  and  tlu  jMisterior  part 
of  the  body  may  be  cut  oft  without  causin^^  them  to 
lea\  c  their  hold. 

".\s  the  pairs  of  C'vclops  ^  swim  through  the  water 
the  males  are  usually  tlu  more  active.  !"rei|uently 
the  female  remains  entirely  i]uiet  with  the  .ippen- 
daj.^es  drawn  close  to  the  body,  ami  the  body  lle\ed 
ventrally,  allowing  herself  to  be  i^assi\ely  carried 
about  bv  her  mate.  .\t  other  times  the  female  may 
swim   as   actively   as  the  male.      In  ^^em  ral  the  be- 


Ill     I     Ml' 


228 


Stuili,^    ni   .lii'inidl   lirJurj'iur 


lia-ini-  .,i  the  tV,MalL>  aiul  tlidr  atrltuj.'  wliiK-  hcinj; 
carncci  cl,)s=  'v  rcscniMc  \vh,,t  is  t.nuui  in  tfic  Ainplii- 
poda.^  S,.  ;,|s(.  J(,cs  thui-  hcha\i..r  wli.n  ilic  males 
COMIC  ill  u.ntaa  with  thcin  and  attempt  to  sci/c  them. 
Hie  te.iialc  Juriii-  the  efforts  of  the  ,nak  to  clasp 
fin-  arouiui  the  base  of  the  alvionun  usually  lies  ,iulct 
with  the  nppemla^r,.s  dy.xwn  close  to  the  body. 

"So  far  as  couKI  he  detected  the  males  d..  iiot  >eek 
or  iollou-  the  fe-nales  at  a  distanee  as  Parker  eon- 
eluded  they  did  in  [.ahidoeera.     'Ihe  association  of 
the  sexcs_ seems  to  he  due  merely  to  chance  collisions. 
Males  often  attempt  to  seize  other  copepods  regard- 
less ot   sex.       Idle  m.des  resist  such  attempts  at'sei/- 
ure  and  dart  (juickly  away,  while  the  females  often 
stop  and  submit  readily  to  the  clasping  propensities 
of  their  companions.     .Several  males  were  injured  so 
that  they  could  not  resist  seizure,  and  In  many  cases 
they  were  seized  by  other  males  who  w.rked' indus- 
triously until  thev  Kot  their  burden  clasped  around 
the  base  ot   the  abdomen  in  the  usual  wav.      Idiesc 
associations  did  not  last   lon<r,   however;  the  active 
males,   apparently  appreciatinjr  that  something  was 
wrong,  soon  swam  away.      Recently  killed  females 
were  often   seized  and  in  some  cases  carried  about 
for  a  while,  but  they  were  finally  dropped."' 

1  here  was  no  evidence  that  odor  determined  the 
sexual  behavior  ni  the  males.  The  males  paid  no 
attei.tion  to  a  number  of  females  that  were  enclosed 
withm  a  tube  whose  end  was  coxered  with  wire 
gau/e.     fn  another  experiment  several  females  were 


'I'll.    Ri  ,  lujiiili'iii   I'f  Sex 


2  If) 


phuiHl  in  a  tuln-  in  wh'uh  a  small  plui;  i>t  loose  cotton 
\va<  iiiscrtcil  a  short  disuiiuc  i  roin  one  iiui.  I  he 
iiiaU's  showoil  no  tciuKiuy  to  ctitcr  the  oiuii  mouth 
of  tfu  tuiK  .i^  tlicv  ininlit  he  expeeteil  to  ilo  it  they 
uei-e  attraeteil  hv  tlie  odor  ct  the  Kmahs.  I  he  e\- 
perliiu  :)t  ot  renioxinL:  tlie  or^aii  ol  smell,  whuh  was 
performed  in  tlie  .ase  of  the  amphipoiis,  wouKl  !>.■ 
a  fruitless  one  in  C\Jops.  as  the  seat  ot  smell  is 
loeated.  to  a  eonsiilei'ahle  ileLjree  at  least,  in  the  s.ime 
orLjatis  th.it  are  used  tor  Jaspm'j;. 

"it  is  evident  that  matin;^  in  C'velops  is  hrouizhr 
ahout  nuieh  as  it  is  in  the  \mphipoda.  I  he  males 
ha\e  a  stronjj;  tcndeiK\  to  elasp  other  cope}iods;  the 
females  tend  to  remain  (]uiet  in  a  condition  some- 
what resemhlini;  the  ile.ith  feint  while  hem^'  seized 
hy  the  males.  It  is  not  improh.ihle  that  olfactory 
stimuli  may  cause  the  males  to  i-emain  with  the  fe- 
male longer  than  they  otherwise  woi.M.  and  they 
may  rentier  she  males  more  prone  to  seize  females 
dian  other  inales.  Init  >o  |;ir  a^  ciuiM  !k'  deter- 
mined hv  watching  the  hehasior  ot  the  anim.ds  the 
specilic  reaction  of  the  two  sexes  to  certain  kinds 
of  contact  stimuli  is  th.e  main  f.i.tor  in  hrin^nn^ 
ahout  tlicir  association." 

In  the  cravtlsh  the  studies  of  \ndrews  and  ot 
I'earse  ha\e  shown  that  sex  recou^mtion  is  effected 
In-  much  the  same  miiliod  as  is  followed  in  the  am- 
jihipods.  Ixtracts  from  the  I'oiiies  ot  females  added 
to  water  contalninj^  die  males  did  not  elicit  the  least 
response.     Nothing  in  the  heha\  lor  ot  the  inales  indl- 


-i,?" 


•^//"/.'<>    /;/   .In'nihil   Hi/iavinr 


tat.s  f|,.,,  ,|hv  arc-  drawn  touarj  thu  t'vmalcs  hy  the 
vnsc  n(  Ml,  •II.  Mating  apparcntiv  Is  Jcpriulcnt 
"I"-"  tlu'  ^Ikhkc  inaririK^s  <.|  fhc  sc\ls.  "Dui-in^r  rlic 
'"■"^'il;  season,"  savs  iVars,.,  "the  instinct  of  rho 
"':il^'  1-  t..  ^rr.isp  an. I  turn  -.n.r  e\cr\  cravtish  that 
^':"'^""'  '"^  '^•'\-  •  •  •  If  thisiujisl.iual  is'a  Icnialc 
"I  the  saine  speues  the  attempt  ,nav  meet  with  suc- 
t^-.^s,  hut  il  it  is  a  male  or  a  female  <.t"  anothcT  species 
the  effort  at  sexual  utnon  is  usuallv  of  short  Jura- 
''""•  "       1 1    in  lies   attempt    to 


mate  with  other  males, 
li\c  resistance, 
>    icinams  pas- 


.1^   ilie\    often   do,    the\    encounter   aeti\e   resistance, 
''"'   ''    ■'    tuiiale   Is  ati.ukej   she   usua" 
si\  e. 

In  fishes  the  males  are  fre.|uentlv  Jistiniruisheil  by 
their  more   eonspiaious   eo|,, ration   espedaliv   durin^r 
the   hreeJin-  reason,       Ihe   (uiunaeitv    and   thrcaten- 
i-K   attitudes   of  the  males  at  this  time   und(,uhtedlv 
cnntnhute   t..   their   mutual    reeo^rnition,   hut   there   is 
iMJcnee  rhat  tlie  mature  males  ot'ten   recuni/c  one 
^"■nther  In   their  peculiar  markin;,^s.      In  her  account 
<'^t   the  hreedm-  h.iblts  <.f  the   ralnhow   darter.   Miss 
Kccves   records   several   cases  of   \oun-  dull-colored 
"lales  hem.uMnistaken  for  females,  nhereas  the  larger 
■'^<^^^  "lore  hrilliantly  colored  adults  usuallv  reco^mi/c 
"lie   an..ther   ^vithout   diflicultv.      "rhe   more   nearly 
the    heh.uior    of    a    dull    male    simulates    that    of    a 
'^■"lale,  as  i„  ,he  ease  of  a  male  hurrouinj^r  tor  food 
tlic  more  is  he  likelv  to  he  taken  f.:r  a  female.     Tpon 
the   near  approach   of  the   hrilllant  male   the   voun-r 
male    erects    the    first    dorsal    and    rapidiv    escapes" 


T'lL   Re  I  iiipiit;'"!  ('I  Si.\ 


2.^1 


IIKhK-,    (if    llclKlvinr    lint    nliSLfX  1>1    ill    tllC     tcilialo.        It 

a|i[)cars,  then,  that  the  hrilliaiit  tish  ilistin^,nii>lKs  the 
two  In  their  beha\inr;  a  iinuie  o(  sex  reeoi^nition 
pointed  nut  In  I  lohius  (  \<t'\'\)  in  the  ease  ot  arnphi- 
pmls.  Iti  the  case  ol  \  er\  youn^  males  the  sex  reco*;- 
nition  must  he  uhnlU  n\  this  character,  while  males 
which  alreaiiv  slmw  sume  little  sexual  CDloration  are 
prohahly  distin}j;uislad  updi.  near  approach  by  means 
of  It  as  well  as  In  behavior."  ' 

Amon^r  the  amphibians  the   reco^niitioii  ot   sl-\  in 
the  fro^i  has  been  tlie  subject  of  several  interestmi,^ 
experiments  In  dolt/.     In  froj^^s  and  toads  the  males 
clasp  the   females  durint,'  the  breeding  season   until 
the   eff^s   are   ilischar^ad   when   the   male   sheils   his 
sperjii  o\cr  them.     What  it  is  that  induces  the  male 
to   dischar):;e    his    sperm    at    the   opfiortune    moment 
when  tile  e^^s  are  [nissin^  I  roni  tb.e  temale  has  ne\er 
been  satisfactoriK  cleared  up.      Ilu  clas[)inj,r  of  t  ro^rs 
insures  that  the  male   i^  on   hand  when   his  services 
in   fertili/iti^  the   e^^s  are   reijuired.       I  he  clas})inj^ 
instinct  is  a   temporary  oik-,  cominu;  on  carlv  in   the 
s(iring.    and   then    ^easin^^    after   the   short   breedin^^ 
period  is   past,    when   the   sexes  scatter   and  pay   tio 
further  heed  to  oiu'  .mother's  existence.      As  is  well 
known,    male    fro^s   and   toails    oitcn    clasp    \ar      is 
objects  durin^i;  the  breedinL";  season.     I'ro(;s  ha\  e  been 
found  to  clas[)  fishes  the  eyes  of  which  they  some- 
times ^ouj^c  out  with  their  thumbs;  and  I  have  taken 
a  male  toad  industriously  clasping  an  old  dried  apple. 

'  Uiolo'ii^iil  BuiUtin,  \  ul.   M,  \>.  ih,  l<^^7 


2,-?: 


St/iJics  in  .hiivial  firlunior 


"U'   .nstnur  to  clasp  is  on.  of  jrrc-at  strcnKth   arul 
"';'  c  toads  ,nay  suf    ,•  thoir  ho.ii.s  to  |,c  cut  in  two 
without  relinquishing  their  hoM  ,,„  the  female. 
_     Correh.teJ   uith   tlie  appearance  of  the  hreedin;,^ 
Histnict  there  occurs  increased  development   of  the 
mncr  dijr.tal  muscles  and  certain  other  parts  of  the 
f-re  le^rs  of  the  males,  a  development  which  \uss- 
I'^Him  has  shown  to  he  checked  if  the  males  are  cas- 
trated  a   considerable   time   before   the  onset  of  the 
lH->edmK  season.      Probably  as  a   result  of  intern  d 
secretions  of  the   reproductive  ^rh„,ds.   parts  of  the 
ncuro-muscular  mechanism  !,ecome  at  this  time  pecu- 
li^'rly  irritable,  so   that  a   partiuilar   f..rm   of  reflex 
activity  IS  very  easily  e^oked.      Hut  notwithstandluLr 
this,  a  frojr  or  toad  seldom  Jasps  for  hrn-^  anvthinir 
nit  the  female  (,f  his  own  kind.     Other  male's  mav 
I^c  clasped,   but  thcN    are  usually  soon    relinquished, 
while  a  fe.nale  is  clasped  the  more  lirmlv  the  longer 
she  IS  held.  ' 

How    does    the    fr<.-   distinf,niish    male    fn.m    fe- 
male  .      Colt/  has  found  that  blinded  *ro^s  discrimi- 
nate   between    the    sexes    as    well    as    normal    fro^s 
Alter  the  olfactory  nerves  were  cut  he   found  that 
ma  es   can  still   distinguish    females,   so  that   neither 
siKht  nor  smell  ,s  a  necessarv  element  in  the  reco.r. 
nmon  of  sex.      Fv  en   when   the   males   were   robbed 
of  both  siKht  and  the  sense  of  smell  manv  of  them 
succeeded  in  clasping  the  females  among  whi.h  thev 
were    placed.       \\-hen    the    females    were    rendered 
mute  by  an  operation  they   were  no   longer  sei/ed 


•  V  t      _J  vy  1     •     \,^  , 


77/('    Re,  nymtiiiH    (if    SiW 


^^^ 


M;iIlS,  (  Kilt/ 


(.dIIlIUiU-U 


ari.'  nut  drawn  towaril  the 


«H 


one   scii>(.'   .ilonc, 


Hit  In   lU'-'an^ 


of 


sc\cral  senses,  no  one  ot  wliieh  is  indispensaMe.  It 
i>  a  s  -ikini:  lac;  that  a  \vn^  whose  head  is  ei;t  in 
two  so  as  to  reni(i\e  tl:e  cerebral  hemispheres  and 

itiniie  to  clasp  a  female  that 


ill 


eves  will  ne\  c  rttieless  con 


tht 


one   o 


( 


is   presented   to    him,    while   he   soon    rejects 
fiis  own  sex. 

'I'he  bodies  of  females  are  commonly  plumper 
than  those  of  the  males.  May  the  latter  perchance 
distinguish  the  females  by  their  form?  (iolt/  tried 
the  ex[ieriment  of  stutlin^  out  the  body  of  a  male 
ivi)^  and  gi\iiig  it  to  another  male,  but  he  tounil 
that  it  was  soon  abandoned.  Does  the  male  troi; 
lia\e  so  delicate  a  tactile  sense  that  even  thou^di 
nearly  brainless  he  cannot  be  decei\ed  as  to  which 
sex  is  within  his  s^rasp?  (iolt/  is  inclined  to  con- 
sider that  such  is  the  case.  It  may  be  open  to  doubt, 
howe\er,  if  the  possil'ility  was  sutHciently  consid- 
ered that  sex  recognition  may  be  a  result  of  the 
behavior  of  the  two  sexes,  much  as  It  was  found  to 
be  in  amphipods.  Desjiite  the  interesting  experi- 
ments of  (iolt/  the  matter  reijuires  further  iinesti- 
•"•ation  before  a  decided  coik  ion  can  sately  be 
drawn. 

In  the  birds  the  sexes  iiiay  often  be  easily  dis- 
tinguished by  sight,  atid  in  many  species  each  sex  is 
doubtless  able  to  recogni/e  the  other  by  this  sense 
alone.  The  discrimination  may  be  aiiled  by  the  ob- 
ser\  ation  of  differences  in  beha\ior.      1  here  is  little 


2.U 


■V/zJ/Vv   ///   .h<i„i,i/   /lilniiinr 


fvi.k'na'   from  rlir  !nli;i\i,.r  of  !,ir.is  t|,;u  rh,-  sais, 


of  sine 
111  tlio 
alikf,  as  i 


1^  rclK-tl  iipnn  m  tins  rn.ittir  to  anv  drj^rn 
ln_  those    hinis    in    which    the    tuo    sexes    are    nuieh 
"  "lost  pigeons,  .ilttercnees  in  heha\ior  ap. 
parentlv  aHorcI   tlie  ehief  means  hv   which   each   sex 
'listin^ruishes  the  other.      Crai^  1,,  his  interestin^r  ;„- 
count  of  tlie  expressions  of  emotions  in  pij,r,.,,ns  '  says 
^''•'^  ""^'    •'   ^''«^'   '"ntaiiiin^r  ;,n   „nmateJ   male    rin^- 
'I'Hc      he      siuhknlv      hrou-hr      ah.ii^rside      another 
(■:'Kc  co„t;nnin«:  another  rin.^-dove.  of  unknown  sev 
the   male  heeonus  hi^rhlv  exeite.l  at  once,   and  yives 
vent    to   his   excitement    in   all    possil^e   wavs.      lirst 
'u'  hous   and   coos  with   all   his  mi.irht.   and   he  con- 
tinues  to   do  so   t'or  a    lonir  time.      Then   he  char;x^.s 
about    the    ca.ire.    assumin^r   the    attitude    peculiar   to 
tfic  char,i,re.   and    fre.juentlv   repeatin-   the   loud  kah- 
"f-cxcitement.      At    intervals    he    stops    to    .^lare    at 
the  st-an^rc  hird  and  sometimes  to  peck  at  it'throu^rh 
the   bars,    hut  soon   he   starts   ajrain   to   how-and-eoo 
and  chart^^e. 

"I»"  left  beside  the  stranger's  ca^v  for  some  hours, 
tlie  male  must  sometimes  rest  and  be  silent •  but 
even  the  mterx  als  of  rest  and  silence  are  broken  frc- 
'juently  hv  series  of  perch-coos.  This  behavior  on 
the  part  ot  the  male  is  useful  in  that  it  stimulates 
the  stranue  h;rd  to  respond,  and.  in  respondin.t^r,  to 
reveal    its   sex. 

"If  ilie  stran^r,.  bird  be  a  male,  it  shows  similar 

">"l-;y  and  rsy,h.,i.„jy,  V..1.    u,. 


'  I  ■•III  lid!  ,'/  c  \ni!(', 


iiii'.i:  ,- 


f  ^t  _j  vii  I 


Tin    Ri,  i',/uili<iii   i>l   Si\ 


}> 


c\i.it(.MKnt   .iiui  ;ijryrcssi\  tiR'^s.      Alul  tlic  tud  males 
arc  sure  to  ti^'lit  it  tlu\   lan   reach  mic  another. 

"Hut  il  .he  strange  l)ird  is  a  t'cmale,  >he  acts  far 
otherwise.  She  is  at  first  \ery  irulittereiit.  unless  she 
is  particularlv  anxious  to  mate.  Aiul  after  some 
ilays,  when  she  begins  to  show  an  interest  in  the 
male,  she  does  not  ^i\e  the  howin^'-coo,  nor  charge 
up  and  down  the  eaij;c,  nor  show  other  sij];ns  of  pug- 
nacity and  a^f^fressi\cness.  So  far  from  tendin^^  to 
a^uress  the  male,  her  conduct  is  rather  an  expres- 
sion of  sulniiission  to  him.  She  shows  a  c-Ttain 
excitement;  for  instance  when  she  utters  the  kah  it 
is  a  kah  c\[)ressi\c  of  gentle  excitement.  Hut  she 
spends  the  jrreater  part  of  her  time  in  alluring'  the 
male  by  means  of  the  nest-calling  performance — the 
nest-callmj;  attitude,  seductive  cooinj?.  and  gentle  tlip 
of  the  wiiij:;s.  She  often  tries  to  ^ct  through  the 
liars  of  her  ca^a-  to  the  male;  and,  failing;  tcj  do  so, 
she  sometimes  lies  dcwn  with  one  side  pressed  against 

the  liars.   .   .    . 

"When  the  male  sees  the  stranj^'e  bird  behaving 
in  this  submissi\e  and  seductive  manner,  he  loses 
the  intensity  of  his  putj;nacity;  though  he  always  con- 
tinues to  be  masterful,  lie  spends  less  time  now 
ii.  the  bowing-coo  and  more  time  in  nest-calling  and 
in  trying  to  get  to  the  temale. 

In  tlie  mammals  the  sense  of  smell  plays  a  much 
larger  part  in  the  recognition  ot  sex  than  it  does 
in  birds  and  the  lower  \ertebrates.  Not  only  is 
the  sense  of  smell  as  a  rule  acute,  but  scent  glands 


2^- 


Sfhli,^    i„   ./niiihil   /hh.iiinr 


'»•    s.MM.iis  kiiuls  are  of   frc.|utnt  ..luirrLfuc  in  ,„ir 
or  l...tli  si-xcs,  and  frc<|ijcMtIy  the  secretin,,  of  tlusc 
K'lanJs  IS  cxa-|)ti,.,i;.llv  alnifulaiit   Juriti^,r  ,}u-   l,rcal- 
I'lK  >oasun.      C  ut.HHunK    sunt  ^laiuls  aic  hcttiT  dc- 
Y''"''"''    '"    '''^-    "••''^     -^^x.       The-    stnM,.y    ,„i.,,    „f 
t  K-   male  K'-at   is   nutcriuus.      |„   tin    „iale   elephant 
there    are    jrh.n.js    ,,„    the    side  <.f  the  fau-    uliich 
•n   the   hreeJinK'  I'^tI.mI,    eiilar^'e    aiul   emit    a    milky 
saretion.     [„  the  males  n(  niat.v  speeies  ..f  Jeer  aru'l 
antelope  there  are   facial  ^huuh  that  are  especially 
active    i„    the    nittinj^r    season.       Other    spe.i.s    ln\e 
seent  K'l.in.Is  on  the  feet  ar,J  Ii„,hs,  or  near  the  tail 
It  IS  not   impr<,l>ahle  that  the  secretion   of  these 
Riaruis,  while  n..t  particularly  ajrreeaMe  to  ourselves, 
may  have  an  allurintr  influence  on  the  ..pposite  sex 
of  the   species   concerned.       There   is   ahundant   evi- 
dence   that    diherent    .species   of   niammals    are    able 
to    reco^rpve   their  oun   kind   through   the   sense   of 
sn.cll.  and  ,t  ,s  a  \yell-kn<.un  fact  that  many  mam- 
mals are  exceedniKlv  (]uick  to  detect  the  scent  of  -.n 
approachmfr  enemy.      \nv  one  uho  has  watched  the 
hchavior  ot  dogs  ,n  taking  a  snitt  at  their  ditlcrent 
aoiuamtances,   or   in  getting  a    fuller  olfactory   im- 
pression   ot    a    stranger,    will    realize    so.ncwhat    to 
f'"u-   great   an    extent   experience   with   odors   makes 
KP    the   dogs    mental    uorld,      .Many    facts   indicate 
that  mammals  distinguish  the  opposite  sex  of  their 
own  species  through  the  sense  of  smell,   but  as  the 
sexes   fre.,uently  difter   in  external   appearance  they 
"-  undoubtedly   able   to   recognize  one   another   by 


are 


Rffcrencci 


237 


si^;ht.  \  tiTiain  t'.iniili.irllv  with  the  habits  ot  street 
lurs  will  coiniiue  imu\  I  think,  that  the  eIet»K'Ut 
nt  l)eha\iii|-.  as  in  seme  ^t  the  i.ases  previously  Je- 
seribeJ.  phiys  a  certain  rule  also. 

I  he  recnjruition  (tt  sex  has  been  Httle  analy/eil 
m  the  inarnnials.  I  he  [irobleni  is  more  eomplex  tliaii 
in  lower  Inrnis  owinn  to  the  hi)j;her  ile\'el(ipriient  uf 
the  inaininaliaii  riiirul.  and  the  taet  that  several  tlil- 
tererit  senses  are  usually  iinoKed. 

RII  I  kl  NCI'S 


\\l)Klus,  I  .  \.  C  Diiju^atiiin  in  the  eraytlsh, 
C  ambarus  atlinis.      jour.    I  \}).   /ool    <;,   l},^,    1  <;  1  i . 

H.Wl  \,  \.  M.  Se\  reeoj^^nition  atul  the  niatin^^ 
beliav  ior  in  the  uootl  I  ro^,  Kana  sylvatiea.  Hiol. 
Hull.  2'),    171,    1914. 

Ck.\1(.,  W.  I  he  expression  of  emotion  in  the 
pigeons.  I,  I  he  bloiul  rin).^  tlove  {  I  urtur  risorius). 
J(»ur.  CciMip.   \eur.  I'syeh.   19,  21;,   19^9. 

I'.MiKl  .  |.  1  I.      Souvenirs  entomolo>^i(]ues,  7  seric. 

(ioi.l/,  1  .  I..  ik-itra^e  /ur  I.ehre  von  ilcn  I'unk- 
tionen    licr    Nerv  enzentren    des    I'Vcjsches.       Berlin, 

isr)9. 

liulMis,  S.  J.  (i)  Observations  on  the  habits 
ot  1  lyalella  dentata.  Seience,  N.  S.  i>,  ^29,  19^2. 
(2)  Sex  recot^nition  ainon^  amphipovls.  Hlol.  Bull. 
5,  2S8,  I9'>;>.  { },)  Sex  recognition  in  Cyclops.  Biol. 
Bull.   16,  3 13,    I9"9. 

l*.\KKl  K,  (1.  11.      Reactions  of  copepuds  to  vari- 


^38 


Sti.Jifj  ill    Iniuuil  Btlunlor 


ous  stimuli,  ct        Bull.  U.  S.   Fish   C 


oni.   2  1, 


1 90 1 . 


103, 


Ki.r.v.s,  C.  D.  The  hrccJinj.  habits  of  the  rain- 
l)ou-  darter  ( I'theost-.tna  ciTuleum  Storer).  a  study 
in  sexual  selection.     Bi,T  Bull.   14,   35,   ,907 


XITT 


111;;  Koi.i.  oi   si.x  IN   iiii.  iNoi.riioN  oi    mind 


I  HI-,  reason  for  tlic  existence  of  sex  is  one  of 
-■■  those  hioloj^ical  (M-ohleius  whose  solution  seems 
as  remote  as  it  liid  a  centur>'  aj^o.  Many  remark- 
able disco',  eries  ha\e  been  made  in  regard  to  the 
microscopic  structure  and  de\eh)pment  of  the  germ 
cells  in  both  plants  and  animals.  We  have  learned 
much  of  the  general  biology  of  sex,  and  the  prob- 
able e\()lution  of  sex  in  the  organic  world.  .\nd 
substantial  progress  has  been  made  with  the  old 
problem  of  the  determination  of  sex.  But  to  the 
question,  Why  came  there  to  be  two  sexes  at  all? 
or  in  other  wonls,  Why  do  not  organisms  continue 
to  rcprotluce  asexually  as  it  is  probable  they  once 
liid?  we  can  only  offer  answers  that,  to  say  the  least, 
are   very   hypothetical. 

While  the  fact  that  sex  is  absent  in  the  lowest 
forms  of  life  indicates  that  evolution  has  proceedeii 
at  least  a  certain  distance  without  its  aid,  and  sug- 
gests the  possibility  of  the  evolution  of  sexless  forms 
of  a  high  degree  of  organization,  yet  the  general 
prevalence  of  sex,  with  but  rare  exceptions,  in  all 
but  the  most  primitive  organisms  points  to  the  con- 
clusion  that  sex  has  played   a    fundamental   role   in 


24t>  Siiuiirs  ill  .hiiiiud  IUIunh,r 

the   evolution   of   the   orjranic   worKl.      It    is  doubt- 
less ^futile    to    conjecture    what    the    orjranic    world 
would  have   been  like   it'  the  institution   of  sex   had 
never  been  evolved.     J-ven  if  the  processes  ot  varia- 
tion and  selection  hail  jrone  on  to  the  same  extent— 
which  is  scarcely  pmbalile— the  absence  of  sex  would 
certainly   ha\e   given    to   evolution    a    \erv    ditterent 
direction    Jn.ni    that    which    was    actuallv'  h.Ilowed. 
Miiny   oi    the    most    complex   of    the   structural    ar- 
rangements   of    organisms    have    especial    reference 
to  securing  the  meeting  of  the  germ  cells.      Ihe  olor 
and  scent  ot    Howe.-s.  and  their  manv  and  beautiful 
adaptations  to  ettect  cross   fertilization  would  never 
have  appeared  if  plants  were  propagated  solelv  by 
the  asexual  method.      In  animals  the  structural'  pe- 
culiarities associated  with  sex  are,  as  a  rule,  among 
the  most  complex  features  of  the  bodv.     Correlated 
with  these  structures  we  lind  mating  I'nstincts  which 
fre(iuently  manifest  themseKes  in  complex  modes  ni 
heha\  lor.     More  acute  senses  have  been  evolved  in 
many  cases  very  largely  in  relati.)n  to  securing  the 
meeting  nt  the  sexes.      The  large   antenna-  of  male 
moths    and    sev.-ral    other    insects,    the    larger    eyes 
of  the  common  drone  bee,  and  the  auditory  appara- 
tus of  the  male  mos(]uito  are  a  ksy  <,f  the  numerous 
illustrations  of  this  fact. 

_     'Ine  various  kinds  of  apparatus  in  insects  for  mak- 
ing sounds  winch  are  found  in  crickets,  locusts,  and 
cicadas  are  dcs  ices  for  drawing  the  sexes  together 
and  tl-.;  complementary  development  of  auditory  or-' 


The  R()!r   II f  S(-\  III   ill,-   F-iiiliitinti  of  Mind      24 1 


^;uis  in  r!ic  same  inscits  lias  ilouhtlcss  hecti  greatly 
turtlurcd  thrnnirh  the  cxnlution  of  thcNC  structures. 
I  he  primary  function  ot'  the  xDcal  a[iparatus  of  the 
vertebrates  was  probably  to  furnish  a  sex  call,  as 
is  now  Its  exclusive  function  in  the  Amphibia.  Only 
later  aiiil  secondarily  tlul  the  voice  cotjic  to  be  cm- 
ployetl  in  protecting  anJ  fostering  the  young,  and 
as  a  means  ot  social  communication.  And  the  evo- 
lution ot  the  voice  in  vertebrates  iloubtlcss  influ- 
enced to  a  nnrked  dep;ree  the  evolution  of  the  sense 
of  hearinjT.  Ir  is  not  improbable,  therefore,  that 
the  evolution  of  the  voice,  with  all  its  tremendous 
conse(iuences  in  regani  to  the  evolution  of  mind,  is 
an  outgrowth  of  the  differentiation  of  sex. 

In  cases  of  degeneration  through  parasitism  or 
other  causes  the  female  often  proceeds  much  farther 
on  the  downward  path  than  the  male.  In  the  scale 
bugs,  for  instance,  the  females  have  lost  their  wings 
and  many  other  structures,  while  the  adult  male  re- 
mains an  active  anil  graceful  winged  insect.  The 
necessity  for  timling  the  female  has  kept  the  male 
from  undergoing  the  ilegcncration  that  has  over- 
taken  the   other   sex. 

Much  of  the  elaborate  organization  of  the  imago 
state  ot  insects  has  reference  to  activities  tiirectly 
or  indirectly  oncerned  with  mating  and  depositing 
the  eggs  in  the  proper  env  ironment  for  the  develop- 
ment of  the  voung  la-  ;e.  There  is  a  relatively 
long  nymphal  or  larv  al  period  chiefly  devoted  to  the 
vegetative   functions  of  assimilating  nutriment,  and 


242 


Siuilit^   ill  .in'twal  Btluiiior 


K'-outh;   in   many  species  the  imag;.,  takes  no    fooj 
"I-  need  take  none,  before  the  e^ffs  are  fertili/.eil  and 
I;Md:   and    in   several    forms   the   mouth   parts   hn\c 
heeome  so  atrophied  that  food  taking  is  impossible. 
Some  insects  mate  soon  after  thev  emerge  from  the 
lHi|>al  i-nerin^r.      I„  the   Ma>-tlies.  which  live  but  a 
sh(M-t  time  in  the  uin^r^d  state  in  order  to  mate  and 
deposit  their  e^r^rs  i„  the  water.  It  is  prolndile  that  the 
inia-^rn  sta^rc  would  'oni,^  a.tro  have  disappeared  were 
It  not  retained  as  a  means  of  effecting  the  union  of 
the  sexes.     .So  also  with  many  other  insects.     In  the 
win.LTod    state    numerous    new    enemies    are    encouni'- 
cred    and    many    lises    are    lost:   in   the   pupa    sta^^e. 
which  pre()arcs  f..--  it,  there  is  commonly  an  exten- 
sne  tearin^r  Jown  of  old  structures  and  the  building 
up  ot   new  ones  ihirini,r  which  the  insect  is  helpless 
ii^ainst   manv    enemies    and    parasites.      There    are 
compensatory  advantages   in   th,;   possession    of  the 
iniajr,,   stage   in   scatterinjr  the   species   into  new    re- 
KioMS.  and  in  many  other  ways  in  the  different  groups, 
but  were  it  not  for  the  necessity  for  preserving  the' 
niaring  acti\ities  which   occur  in  this  period  of  the 
insect's  life-history,   it  is  probable  that  the  complex 
orgam/atn.n    of    the    adult    state    would    verv    fre- 
quently  ha\e   degenerated,   or  e\  en   been   lost',    if  it 
had  not  failed  to  develop  at  all. 

I  he  mating  acllvities  are  almost  everywhere 
:nnong  the  most  complex  (K'r'ormances  of  an  ani- 
niaTs  lite.  The  op[)osire  sex  must  be  distinguished 
In.m  all  other  creatures  and   responded  to  accord- 


•  »l     -i  Ol    I    V^-l. 


Thv  Roll-  nf  ,S/A  bi   llir  Kx'i'.iii'uni  of  Mhui      24^ 

inj^ly.  <  )ftcn  [uirsiiit  ami  captun.'  or  winning  ()\  cr 
arc  the  necessary  preliminaries  of  inatiMir-  All  this 
puts  a  preniium  so  to  speak  on  the  sharpeninj^  of 
the  senses,  the  tle\elopinent  of  stren;.^th  and  aciite- 
ness,  anil  the  eNolution  ot  higher  psychical  (jualities. 
Consitler  the  mating  activities  of  crustaceans,  the 
courtship  of  spiders,  the  hreedinu;  activities  of  fishes, 
and  still  niore  the  elaborate  wooinjr  of  niale  hirds, 
ami  it  will  become  niani.est  how  greatly  the  insti- 
tution of  sex  must  ha\e  stimulated  the  exolution  of 
more  complex  fiioiles  of  bcha\ior. 

.All  the  facts  here  cited  are  trite  enout^h  e\  en  to 
the  non-biolo-^ical  rt  ••der.  Hut  while  it  is  sufficiently 
evident  that  the  tliHerentiation  of  the  sexes  has  pro- 
moted the  de\  elopment  ot  beha\  ior  in  »•  lation  to 
mating,  it  may  be  well  to  point  to  tlie  enormous  in- 
dir'jct  C()nse(]uence  of  this  development  in  respect 
to  the  evolution  of  mind  in  general.  Fn  the  evolu- 
tion of  behavior  one  kind  of  instinct  grows  out  of 
another  just  as  njw  organs  are  usually  formed  bv 
the  elaboration  of  some  pre-existing  structure.  A 
general  elaboration  of  instinctive  reactions  in  re- 
gard to  any  one  sphere  of  activity  aftortls  a  basis, 
therefore,  for  the  difterentiation  of  more  complex 
or  specialized  behavior  in  respect  to  other  activi- 
ties. The  primary  function  of  the  voice,  as  has  al- 
ready been  pointed  out.  was  to  serve  as  a  sex  call, 
later  it  became  the  means  of  various  instinctive 
forms  of  communication  and  finally  affordctl  the 
medium  of  articulate  language.     I  lad  it  not  been  for 


244 


Sliidh's  in  ./iiiiiuil  Bchininr 


Its  value  in  the  matinjr  r)f  the  lower  \  crtc!. rates  the 
voice  might  never  ha\e  l)een  evoked  aiul  man  never 
ha\e  become  man. 

While  the  specialization  of  senses,  whiefi,  in  cer- 
tain cases  at  least,  has  been  carried  on  mainly  for 
sexual  purposes,  naturally  afforded  a  basis  for  the 
elaboration  of  many   instincts,    it  is  practically   im- 
possible to  trace  in  detail  how  various  instincts,  sex- 
ual and^  other,  may  have  acted  and  reacted  on  one 
another's  ile\  elopment.     Hut  we  can  discern  enough 
of  the  influence  of  sex  differentiation  on  the  evolu- 
tion of  behavior  to  feel  assured  of  its  importance. 
The  necessity  of  solving  the  one  problem  that  con- 
fronts all  divL-cious  animals  which  do  not  simply  shed 
their  sexual  products  at  random  into  the  water  has 
kept  behavior  in  one  sphere  up  to  a  certain  mini- 
mum standard,     ihe  male  must  iind  and  impregnate 
the  female,  and  this  fact  sets  a  certain  limit  to  his 
degeneration,    at   least  in   some   period  of   his  life. 
But  besides   acting  as  a  check  to  degeneration,  the 
necessity   for   mating  has,    in  general   been   a   con- 
stant  force  making  for  the  evolution  of  activity,  en- 
terprise, acuity  of  sense,  prowess  in  battle,  and  the 
higher  psychic   powers.      We   cannot  pretend  accu- 
rately to  gauge  its  role  in  the  evolution  of  mind,  but 
It  has  evidently  been  a  factor  of  enormous  potency. 


XIV 


rill      MINI)    OI      A    MONKI'.V 


T  l/./.\\  was  first  seen  in  a  store  on  Market 
■*-^Strcet,  San  I'rancisco,  where  she  was  confined 
in  a  cage  with  a  small  puppy  which  was  put  in  for 
cf)mpany.  She  was  a  specimen  of  honnet  monkey, 
Pithictis  sininis,  ami  she  had  been  recently  importeii 
from  India,  so  her  owner  averred,  but  during  her 
short  captivity  she  hail  come  to  be  quite  tame  and 
tractable.  A  few  days  later  she  became  the  prop- 
erty of  the  University  of  California,  and  was  kept 
in  a  cage  especially  constructed  for  her  reception 
in  a  sort  of  storeroom  belonging  to  the  department 
of  /oology.  Owing  perhaps  to  the  strangeness  of 
her  new  surroundings,  or  to  the  loss  of  her  old  as- 
sociates, I,i//.ie  frei]uently  gave  vent  to  a  plaintive 
cry,  but  she  seemed  tfi  be  appeased  when  any  one 
came  near.  When  let  out  of  her  box  she  began  to 
scamper  about,  climbing  up  tables  and  other  objects, 
and  examining  things  critically  all  about  the  room. 
If  approached  she  would  often  utter  a  sound  resem- 
bling a  bark  and  stand  with  her  mouth  open  in  a 
threatening  attitude,  at  the  same  time  being  on  the 
alert  to  make  her  escape.  She  proved  to  be  re- 
markably agile,  even  for  a  monkey,  and  very  quick 

-45 


24^. 


Sl/iili,  s    in  J, lima/   Hrhaiinr 


Jto  (lisa.vcT  the  least  niovcmcnt  anywhere  within  her 
ran^a-  of  vision.     She  wouKi  move  about  ahiiost  con- 
.stantlv,    hut   her   attention    was   not  directed   to   any 
"lie  ohjcet  for  more  than  a   few  seconds  at  a  time. 
_     I.i//ie  showed  a   stroii^r  asersion  to  hein^  taken 
l"i  the  han.is.  althou.uh  she  so.,n  came  to  jump  upon 
niy  shouMer  and  ride  about  there  (luite  cntenteilly. 
Often   when    I   stretched  (uit  my  hands  to  sei/.e  her 
she  would  bound  past  them  to  mv  arm  and  (]uickly 
scamper  to  my  shoulder.      It  was  difficult  to  ^ct  hold 
of  her  m  that  situation,  for     le  would  clamber  about 
over  my  body  in   a    very  nimble  wav  in   her  efforts 
to  avoid  seizure.     She  was  fond  of  diving  into  my 
pockets  and  extracting  articles  therefrom  and  then 
scampering  away  with  them.     She  appeared  to  take 
;i   certain   pleasure   in   being  pursued    for  the   recov- 
ery of  the  stolen  propertv.      Most  things  which  she 
took  went  straight  to  her  mouth.     She  was  especially 
fond  of  chewing  up   lead   pencils,    and   took  an   ap- 
parent delight  in  breaking  things  or  pulling  them  to 
pieces.       \tter  a  detailed  in\  estigation  of  an  object 
ior  some  minutes,  during  which   she  turned  it  over 
and  over  with  her  hands  and  feet— for  she  was  al- 
most as   facile  in  grasping  things   with   her   feet  as 
;with   her  hands— she   usually  wearie.l  u{  her  play- 
thing and  gax  e  it  Ttt'e  further  attention.     This  sort 
of    intellectual    curiositv    ati'orded    her   many    things 
with   which    to   occupy   herself;   and   when   no   othc'r 
object  engaged  her  attention   she   would   freijuently 
busy  herself  with   inspecting  her  own  person  in  the 


'I  lu     MniJ    ../    ,/    Monk. 


-47 


pursuit  lit  piissiMf  p.ir.iNitcs. 

One  Miarkcii  trait  o*'  l-iz/ic's  lKlia\ii>r  uas  the 
case  uitl)  which  shr  hciauK  ahirruid  at  anv  unusual  I 
ohjci't  tir  oiiurrcm  I'.  Alter  some  months  ot  ae- 
tjuaititaiue.  when  she  would  sit  eonteuteilly  i>n  my 
sluiiililer,  an\  (|uii.k  ino\  eiiunt  wimM  inspire  her  with 
fear.  A  c^rraiii  instiiKti\e  dread  ol  hein^  taken  un- 
awares seemed  to  be  an  ineradical'tle  part  ot  her 
mental  make-u[i.  P)red  to  a  life  of  continued  watch- 
fulness and  fear  in  tlie  forests  ot  In.  r  nati\e  home, 
she  was  gifted,  to  a  \ery  unusual  degree,  with  the 
faculties  ;hat  make  for  the  re.idy  detertion  and 
avoidance  of  danger,  lor  keetmess  ol  perception, 
rapidity  o(_  action,  facility  in  lorininjf_  good  prac-  | 
tical  judgments  about  ways  and  means  of  escaping 
pursuit  and  of  attaining  \arious  other  etuis,  la/zic 
had  few  rivals  in  the  animal  world.  She  freijucntly 
surprised  me  by  getting  out  at  a  half-opencti  iloor 
which  I  thought  I  had  ettectually  guarded,  or  in  gra'o- 
hing  a  bit  ot  food  trom  me  which  I  was  confident 
she  could  not  reach.  I  ler  perceptions  and  decisions 
were  so  [iiuch  more  rapid  than  my  own  that  she 
would  freiiuenily  transfer  her  attention,  decitle  upon 
a  line  of  action,  and  carr\  it  into  effect,  before  1  was 
aware  of  what  she  was  about.  I  ntil  1  came  to 
guard  against  her  nimble  anil  unexpected  maneuvers 
she  succeeded  in  getting  possession  of  many  apples 
and  [)eanuts  which  I  had  not  intended  to  gi\e  her 
except  upon  the  successful  [performance  of  some  task. 

In  disposition  l.i//ie  u.is  gentle  and  tractable,  and  ' 


MS  .S/,„/„  ,  ,„  ./„,,„„/  /(,./,,,.,„^ 

'•■"■M  "M,.  s  l,:„„|.     O,  afl„ti,.„  or  a„ad,M„n,  ,o 
"f  .""..keys,     ,,„i,  ,,,„„,,,  ^„^^^|  '^'^'^'^ 

:;;;:!    V''«'«"l!"'-"'"inini  a 'ncuki:, 

''''V'  ''""  »"  ^'""tinnal  .a.isfacti,,,,   such  as 
■'  -I'l'  'akcs  ,„  l„s  ,„as,cr.     \Vlu„  she-  was  irri.a  n| 

,  '  ""  "'  "'"ipi-T  «  .re  off  vcrv 

|.U       orshc„asvcTy,ha„Kc.ahlc;,,  her™,,,., 
•>^  «   M   as  ,„   her  mental   pursuits.      She   was  nk 

.,-,Kv,,.er  her  fears.     Wi.h  her,  suffiei™t    :,  . 

She  wa       I  "  ""  ""■""■"'  ""^  ""-■  "il  'h"-f 

ilr.l  r    ""      "'■  '"  ™'-"»P"'i"n:  she  hve,!  en- 

nr    y,,,te, -resent,  n,,.l  in  ,,„,„,  „.,„,„.,„.' 

nu.  h     is, ,  7"  ""."  '"""  ••"''"'"I'ly  ^-ffi-'-t  little 
.'"•'"'7    f'"^  K«t„,K   „n    in    lif^    ^,,,1         1^ 

>   t„,„s  „f  a  tropical  forest,  she  pr,n  e.l  t„   ,e  „  it" 

of  i,,r,:,-.l   I "^"^  *  "^age  was  made 

'     -crt.cl   bars  ,vh,ch   were   far  enough  apart  to 

i  "V  her  to  reach  out  her  arm  hetwee'n  th  m 
h'ard  was  placed  ,ust  oiUside  her  cace  an.l  n  ,V 
"I  -'ri'l''  put  on  the  hoard  hevond  h     ^reac        T  ■ 
«tahhed  at  the  apple,  pushing  the  b"ard  to  on!-!^:: 


Tlir   Mind   of  a  Mi'nkt-\ 


249 


Then  she  trie  '  U)  seize  the  boaril  by  one  eml  aiul 
pull  it  toward  her,  hut  as  the  board  was  a  little  too 
heavy  for  her  to  move  well  in  this  manner,  a  nail 
was  clri\en  in  the  miilille  of  the  end  of  the  board 
nearest  the  cajje  to  ser\  e  as  a  sor   of  handle.     When 


C«.^ 


n. 


U 


rt 


Fid.    11.     Diiigr.im   of   Lizzie's   cjijr<-   with    tin-   Imiird    H,   mi    wliicli 
food  Wii.s  pliucd.     II  n,  (iii^itinn  of  iiaiK. 


board  and  apple  were  placed  as  before  Liz/.ie 
reacheil  immediately  for  the  nail,  pulled  the  board 
in  and  got  the  apple.  A  repetition  of  the  same  ex- 
periment was  followed  at  once  by  the  same  result. 
During  the  third  trial  Lizzie  attempted  to  seize  the 
board  by  the  side  and  pushed  it  away  out  of  reach. 
When  the  lioard  was  replaced  she  pulled  it  by  the 


;    ''''''7'-  ';'S'-'.,n   ..r  ,lu.   situation   tfut   the 
;'''  T   ""'"'""   "''^    .v;.v.      I  Ic-,-  first 

--    -l.a.Iuiu.nUu.n.nIu...lnv..inM^ 

'•'''""  '"  '"':>>•>!,  nail  .1.1:1  ,:,,,,K.. 

A'tii-  the    lourtli   ti-;  il     ul„-n  fl,  •   l„         i 
I  "    II,  \\  III  n  rtu   lin.iic    was  m  itn 

'^    ;""'.l-"-'   "    ">   .Mt.r   o.n..K,,M,    effort'       J 
^"\.-l'-t.n,oM    .It    the    usual    r.uarJ.      This      ,fi,, 

^■'"r"    -^   '-'-•- --icof-tlu'Lar;!      'w 

•^'-l.'it    ,s.xn,nes.   aftc.uhuh   shesatlookin. 

•'f  f''-  .'i-ple  and  uhinin-.       /hen   /  .,!•.,■■)  .1 

on   ,1,,.   ! .     .   .  ■   ,        "    .       '"^   '   1'''"^''  f'H-  apple 


Oil    the    h 


'  ''"^"■''-   ^^''i^''    ^vas  irnn.e.liately  pulle.l  hi   h. 


/■//.      Mm, I    'I    .1     \h.>ik,\- 


1 ;  I 


fill    II. III.       \litr   Ikt   .ipi'.-tlti'   u.i>   uliittnl    .mniliir 

1'ii.t.C    ot     .IppK-    W.ls    |.|.n.(.il    six     iiulus    Id    iMU     s|>K     ill 

till-  I'oartl  .is  Icliiii.'.  I  i//it-  lAiHAl.mtK  pulK.I  the 
I"i;iril  in  .mil  itp  itij  tlu  pt  ii.Miii.iiut  s,\  mure 
times,  hut  lur  a  imiis  !n.i.imc  -li^^srr  with  i.iJi  ilis- 
app(iiiitt)U'n.t,  .mil  at'trr  the  sixth  til.il  she  ^.i\e  the 
huaiil  ii[)  ,iihl  trieil  to  le.n  h  the  .ipple  (hnal) .  I  lien 
.  heKI  the  apple  iK.ir  die  ca^e  to  ^'i\e  her  .1  smell 
">  it  aii>l  ri'j)l,n.eei  it  ne.ir  the  lio.irJ.  I^'iiij^r  thus 
stimulated,  Liz/ie  pulkd  the  ho.n.l  in  li\  th,  n.iil 
three  times,  when  she  L,Mve  up  the  task.  After 
heiii^  tempted  as  before  she  pulkd  the  enijU)  hoaul 
ill   three  times. 

In  these  experiments  I  i//ii-  showed  th.it  she  li.ul 
associated  the  act  of  pullinj;  in  ihe  hoard  h\  the' 
nail  uiili  cht.iinin;,'  a-.d  enjoyinj^  the  a|  j  !  •  Dut  her 
persistence  ■;  puliinj^r  in  the  hoard  when  she  eouKl 
dearh  ■■•!•  tha;  the  apple  was  se\eral  inches  au.iy 
trom  it  showed  that  she  exercis  ,1  little  d'scrimina- 
tion,  and  indicated  that  the  associations  slu  had' 
formed  were  ol  a  ratlier  \.iL;uf  and  ha/y  kind. 

In  another  ex()eriinent  I  [ihued  the  apple  further 
out  on  the  same  hoard  so  that  she  would  he  un.ihle 
to  rcaJi  the  food  wlien  the  mar  end  of  the  hoaril 
was  a^rainst  the  base  of  her  ca^e.  [.i//ie  pulled 
the  hoard  in  at  oiue  .ind  reached  for  tfie  a[)iile. 
lindin^  it  too  f,ir  out.  she  pushed  the  end  of  the  I 
hoard  sidcwise.  at  the  same  time  keeping  it  ajrainst  1 
the  base  ot  the  ca^^'.  This  !-.rouL,'lit  the  apple  ne.trer 
and  she  ^ot  it.       The  experiment   w.is    repeated   se\- 


-5-  SliiJics   ill  .liiimal  Bcfuninr 

cnil  times  and  I  i//ic  sclvcd  her  prohlnn  cad.  time 
with  Iirtlr  or  no  hcsitarion.  as  In  the  llrst  trial. 

'Ik'  problem  uas  then  iiuule  a  little  more  cii.nei,lt 
In   piacm^r  the  apple  still  farther  out  on  the  hoartl 
so  that  she  cuKI   not  reach   it  even   when   she  had 
pushed  the  eiul  o.    the  hoard  as  far  to  one  side  as 
the  limits  of  her  ea^e  uould  permit.     When  she  had 
Pi'llal   the    hoard    in    and    to   ..ne   side,    liMdin^r   that 
the  apple   was  still  out  of  reach,  she  tried  to  sei/e 
the  hoard  hy  the  side  and  to  pull  it  in  sidewise       It 
was  too  difficult  for  her  to  jret  a  jrood  hold  of  the 
l^-'ard  m   this  way,   and  h..  attempts  were  not  suc- 
cess ul.      [    then   drove   a    nail   near   the   middle   of 
the  board,      (.ettm^r  the  apple  Involved  pullln-r  the 
board  to  the  ca^a-  by  ^he  first  nail,  pushinjr  jt'then 
to   one   side   so   as   to  brinjr  the   second   nail   within 
reach,  sei/in^  the  hoard  hy  the  second  nail  and  pull- 
nijr  It  sidewise  toward  the  ca^c  until  the  apple  was 
sufficiently    near.      At   her    first   trial    Liz/ie    pulled 
the  board  in  hy  the  first  nail,  then  pulled  it  sidewise 
and  tried  to  sei/.e   the  ed^r,.  „f  the  hoard.       \ppar- 
cntly  by   accident  her  hand   struck  the   secnd  nail 
which  she   sci/ed  at  once,   and  by  Its  means  pullecl 
m  the  board  and  K<,t  the  apple.     In  the  second  ^rial 
l^i/zie    pulled   the    hoard    in    and    to    the    left,    then 
reached  immediately  for  the  second  nad  and  pulled 
in    the   board   toward   her  ca^e.      In    several   subse- 
.Muent  trials  she  secured  the  apple  In  just  the  same 
way.      1  he  problem  was  s.-JNcd  pcrfectiv  after  the 
first  trial. 


The   Mill, I   of  n   Mi,iikt\ 


•!5.? 


In  another  set  of  cxpLTimcuts  Liz/ic  was  ^i\cii  a 
vascliiif  hottk'  containiii^r  a  peanut  and  ciosci.!  with 
a  cork.      In  accordance  with  her  instinct  to  bite  at 
new  objects  Li//ic  attacked  the  cork  with  her  teeth.  I 
pulled  it  out  and  trietl  to  chew  it,  hoUhnjr  the  bottle 
meanwhile   in  one   hand;  then   she   noticed   the   nut 
when  she  transferred  the  cork  to  her  feet,  and  trieil 
to  reach  the  nut,  but  the  neck  of  the  bottle  was  too 
small  for  her  hand  to  entei      Un  turnin^r  the  bottle 
<)\  er  the  nut  dropped  out  unobserved  and  I  replaced  ' 
It  and  put  in  the   cork.      Lizzie  immediately  drew 
the  cork  und  held  it  in  her  hind  feet  while  she  tried 
to  reach  the  nut  with  her  fingers.     Finally,  when  she 
was  holding  the  bottle  upside  down,  the  nut  came  ' 
withm  reach  of  her  lingers  and  she  got  it  out.     When 
given  another  nut  in  a  corked        tie  she  pulled  the 
cork  and  tried  to  reach  the  nut  w'th  the  bottle  up- 
right,  but  in   the   course  of  her  eftorts  she   turned 
the  bottle  over  so  that  the  nut  fell  down  within  reach,  ' 
when  she  got  it. 

Without  describing  in  detail  her  subsequent  trials, 
I  may  say  that  Lizzie  gradually  came  in  the  course 
of  fifteen  trials  to  turn  up  the  bottle  very  soon  after 
she  received  it  and  to  get  the  nut  much  more  quickly 
than  at  first.  She  never  came  to  turn  the  bottle  over  i 
and  let  the  nut  drop  out.  She  was  too  busy  trying 
to  reach  it  with  her  fingers  to  get  it  by  the  easiest 
method.  Lven  after  she  had  come  to  get  the  nut 
rather  quickly  she  often  spent  considerable  time  in 
attempting  to  reach  the  nut  when  the  bottle  was  held 


2  54 


.S/,7-//V,»   /■;/   .hi'iwdl   ll,Juii'ti>r 


eiprijrlit.      She    ,ii,l   not   pick   out   the    cssenriul    acts 
that  ltd  to  success.     SIic  pcrcciv  cil  that  the  nut  could 
Iv  secured  hv  .^oin-r  through  a  certain  scries  of  mo- 
tions,   ami    t!ie    useless    Diovcniciits    were    jrradually 
chi7iinate(l  witli  an  a\erajrc  shortening  of  the  time 
necessary   to   '^:\\n   tlie   doirccl   end.      So    far  as  her 
proujress    is    concerned    after    she   had    removed   the 
cork  from  the  bottle,  she  Ka\  c  no  evidence  of  clearly 
ll'crceixin.L,^  hou-  anything  that  she  did  furthered  her 
IHirpose.      Apparently  she  did  not  clearly  apprehend 
tliat    il    she   Xuvn^d   the    hottle    upside   down   the   nut 
would    tail    d.iwn    uliliin    reach    of    her    lin^rers,    al- 
th<.u.-h   she  had   seen   the  nut   fall  do/ens  of  times. 
In  the  course  of  her  intent  elf(.rts  her  mind  seemed 
s<.   absorbed   with   the   object  of  desire   that  it   was 
ne\er  tocussed   on  the   means  of  attaininj^r  that  ob- 
ject.      Ihere  was  no  deliberation,   and  no  discrimi- 
natK.n   between  the  important  and  the   unimportant 
elements  ot  her  beha\  ior.      ihe  ^r,-avlually  increasing 
facility  ol  lier  performances  depended  un  the  appar- 
ently unconseious  e!iminati.,n  (.f  useless  movements. 
Ihe   |-re\ious  experiments  were  modified  by  giv- 
ing  l.i//ie  a   nut  In  a  screw-cap  Mason  jar  without 
a  cover.     .She  could  easih   reach  into  the  wide  mouth 
and  .i^et  the  nut,   but  she  picked  up  the  jar  instead 
and  turned  it  about.      I  lavin^r  accidentally  dropped 
the  jar.  she  scuttled  awav  in  alarm,  but  she  cautiously 
approached  it  aij:ain.  turned  it  o\  er  and  jrot  the  nut. 
I  hen  she  picked  u(^  the   jar,  carried  it  to  her  perch, 
n-llmir  ,t  over  and  over  with  her  hands  and  feet  in 


The   Mind   <if   a   Mnnkrx 


various  ways.  I  took  the  jar  and  put  anotlkT  nut 
in  it,  but  I.i//ic  continued  to  play  with  the  jar  and 
let  the  nut  drop  out  unobserved.  When  the  nut  was 
replaced  Li/zie  tried  to  get  it  by  bitinjr  the  k'^'^'S; 
in  the  course  of  her  turning  the  bottle  around,  the 
nut  dropped  out  and  she  pickeil  it  up.  When  an- 
other nut  was  put  in  I.i/zie  reached  in  at  once  and 
got  it.  Another  nut  was  obtained  in  the  same  way, 
but  at  the  next  trial  she  turned  the  jar  around  in' 
various  ways  until  the  nut  fell  out;  and  in  numerous 
other  trials  on  different  days  she  sometimes  got  the 
nut  by  reaching  it  directly  and  at  other  times  by' 
turning  the  bottle  around  until  the  nut  dropped  out. 
Tifty  or  more  trials  did  not  teach  her  to  secure  the, 
nut  at  once  by  inverting  the  bottle.  While  she  came 
to  get  the  nut  by  reaching  into  the  jar  more  often 
than  she  did  at  first,  she  did  not  settle  down  to  any 
unifonn  method  of  procedure. 

When  a  nut  was  placed  in  the  jar  and  the  cover 
screwed  on  very  loos  ly.  Lizzie  tried  to  pull  the 
cover  off  by  using  her  hands  and  teeth.  .After  much 
effort  she  succeeded  and  held  the  jar  with  a  hand 
and  a  foot  and  the  cover  with  the  other  hand.  The 
novelty  of  the  cover  engrossed  her  attention  and  she 
let  the  jar  drop.  Soon  she  went  to  the  jar,  reached 
in  and  got  the  nut.  and  then  resumed  her  investiga- 
tion of  the  cover. 

.Another  nut  was  placed  in  the  jar  and  the  cover 
screwed  on  very  loosely  as  befoie.  Lizzie  took  the 
jar  to  her  perch,  worked  the  cover  off  with  her  hands 


2^-6 


Studii's  in  Jiiimal  Behavior 


and  teeth,  and  then  reached  in  and  got  the  nut,  hold- 
ing tlic  jar  upright  with  her  feet.     The  next  trial 
resulted  in  practically  the  same  way.     The  cap  of 
the  jar  was   then   screwed   on   farther.      Lizzie   at- 
tacked the  jar  industriously  and  finally  removed  the 
-'ver,  although  working  quite  unsystematically.    The 
cr)ver  was  put  on  as  before  and  Lizzie  worked  at 
It  aI)out  fifteen  minutes,  getting  more  and  more  ex- 
ntcd  and  mipatient  over  her  lack  of  success;  some- 
times she  tried  to  bite  through  the  glass  at  the  lower 
edge.     After  turning  the  cover  this  way  and  that 
she   finally   unscrewed   it   and  got  the  nut.      After 
jnumerous  trials  Lizzie  never  learned  to  unscrew  the 
|cover  by  turnmg  it  around  uniformly  in  one  direc- 
tion.    She  simply  worked  it  back  and  forth  until  it 
happened  to  become  entirely  unscrewed. 

I-i//.ie  was  then  set  to  the  tasK  of  getting  food 
^'t  of  a  small  box.     Two  sides  of  the  box  were 
"lade  of  strong  wire  netting ;  the  rest  was  wood.     In 
one   corner  was  a   small  door  which   could  be   fas- 
tened by  a  hook  passing  through  a  small  screw  eye 
In  the  hrst  experiment-  a  piece  of  apple  was  pbced 
in  the  box  and  the  door,  which  stuck  r:.ther  tightly 
was    eft  unhooked.     Lizzie  looked  at  me  while   I 
put  the  food  through  the  door  and  she  opened  the 
dnnr  at  once  and  got  the  food.     She  did  the  same 
:!    the  second  trial,  after  which,  when  the  food  was 
replaced,   the  box  was  turned  so   as  to  lie  on   an- 
other side      This  seemed  to  disconcert  Lizzie  and 
she  tried  biting  and  clawing  at  the  wire  netting,  and 


The  Mind  of  a  Monkey  257 

turning  the  box  over  and  over  until  she  became  dis- 
couraged.    I  recalled  her  to  the  task  by  tapping  on 
the  box,  hut  evoked  only  feeble  efforts.     When   I 
opened  and  closed  the  door  Lizzie  observed  me  and 
went  at  once  to  the  door  and  got  the  apple.    Then 
I  replaced  the  apple  and  closed  the  door  and  put  th  i 
box  in  another  position.     Lizzie  attacked  the  box 
in  various  ■  laces  and  then  desisted.    Soon  she  looked 
at  the  be      went  to  it  as  if  an  idea  struck  her,  and 
tried  to  pull  the  door  open  by  using  hands  and  teeth; 
finally,  after  some  tugging,  she  succeeded.    After  a 
few  more  successful  trials  the  door  was  fastened  with  \ 
the  hook.    Lizzie  attacked  the  door  with  hands  and  ' 
teeth  and  turned  the  box  over  and  over  and  often 
tried  to  get  the  apple  through  the  wire.    A  renewed 
attack  on  the  hook  enabled  her  to  get  the  door  open  • 
and  get  the  apple.    The  next  trial  on  the  succeeding 
day  was  followed  by  much  the  same  method  of  at- 
tack.    After  biting  at  the  hinges  and  various  other  , 
parts  of  the  box  Lizzie  loosened  the  hook  and  opened  ' 
the  door. 

Not  to  weary  the  reader  with  the  recital  of  Liz- 
zie's misdirected  efforts  and  slow  progress,  it  may 
be  said  that  she  gradually  came  to  concentrate  her 
efforts  on  the  door,  but  even  after  thirty  trials  she 
would  bite  at  the  hinges  and  edges  of  the  door,  ' 
and  not  infrequently  she  would  turn  the  box  over 
and  bite  at  the  wire  netting.  In  all  of  her  efforts 
at  the  hook  she  never  learned  to  pull  it  to  one  side.  ' 
She  simply  tugged  at  it  this  way  and  that  with  her 


258 


Studies  in  Animal  Behavior 


teeth  until  it  came  undone.  The  mechanism  of  the 
thinjr,  hinv  the  hook  stood  in  the  way  of  opening 
the  door,  she  could  not  understand,  simple  as  it  was. 
When  a  button  was  substituted  for  the  hook  her 
mode  of  attack  was  much  the  same;  and  her  prog- 
ress, such  as  she  made  in  rhc  course  of  thirty  trials, 
was  after  the  same  slow  method.  She  never  per- 
ceived that  when  the  button  was  turned  in  one  di- 
rection it  left  the  door  free  to  come  open,  and  that 
it  prevented  the  door  from  coming  open  when  it 
was  in  another  position.  She  bit  and  worried  away 
I  at  the  button,  and  pulled  at  the  door  until  she  got 
it  open  and  got  her  food.  The  idea  of  the  thing 
never  got  into  her  head. 

When  both  the  hook  and  the  button  were  used 
I.i/zie  had  a  very  hard  time  to  get  her  food.  Oc- 
casionally after  much  varied  and  fruitless  effort  she 
would  succeed.  If  she  got  the  button  turned  right 
jshe  would  usually  turn  it  the  wrong  way  before  she 
undid  the  hook.  The  experiments  would  probably 
have  discouraged  her  observer  hid  they  not  usually 
wearied  their  subject  before  she  met  with  success. 
There  was  little  hope  that  she  would  be  able  to 
solve  more  complex  problems. 

A  peanut  that  was  hung  below  her  at  the  end  of 
a  cord  she  obtained  by  pulling  up  the  cord,  hand 
over  hand,  the  very  first  time  she  saw  it.  I  tried  to 
teach  her  to  use  a  stick  to  pull  in  food  with,  as 
monkeys  have  sometimes  been  described  as  doing, 
'  but  met  with  no  success.    Placing  a  bit  of  food  out- 


The  Mind  of  a  Monkey 


259 


side  the  cage,  I  poked  it  about  with  the  st.ck  so 
as  to  give  her  a  suggestion  of  how  the  stick  .night 
be  employed  to  move  the  food  within  reach,  hut  al- 
though the  act  was  repeated  many  times.  Li//ic- 
never  showed  the  least  inclination  to  use  the  stick 
to  her  advantage.  In  fact,  she  never  exhibited  the  | 
least  tendency  to  use  any  object  as  a  tool 

Next  I  tried  suspending  a  piece  of  food  beyond 
her  reach  and  giving  her  a  light  box  upon  which  . 
she  might  mount  and  get  the  food.     She  did  this 
readily  enough  when  the  box  was  in  the  right  posi- 
tion.    Then  the  box  was  pulled  to  one  side  in  or- 
der to  see  if  she  would  pull  it  back  so  that  she  could' 
get  upon  it  and  reach  the   food.      Although   I   fre- 
quently moved  the  box  about  to  give  her  the  sug- 
gestion and  often  put  it  in  the  proper  place  to  en- 
able her  to  get  the  food,  the  idea  of  using  the  box 
in  the  way  described  never  seemed  to  occur  to  her. 
Experiments  with  Lizzie  were  brought  to  a  close 
by  her  death,  but  the  results  obtained  were  sufficient 
to  give  some  insight  into  the  nature  and  limitations 
of  her  mental  endowments.     While  gifted  with  re- 
markably quick   perception   and   in  certain   respects 
power  of  rapid  judgment,  nothing  in  her  behavior 
gave  any  indication  of  the  use  of  abstract  or  gen- 
eral ideas,  or  of  deliberate  reasoning.     Neither  did 
she  exhibit  the  least  tendency  toward  imitation,  al- 
though I  am  not  prepared  to  say  that  further  ex- 
perimentation might   not  have    revealed  some   evi- 
dence of  this  faculty.     Some  things,  and  even  sim- 


26o 


Studies  in  Animal  Behavior 


pie  things,  she  apparently  learned  by  the  primitive 
method  of  the  gradual  elimination  of  useless  move- 
ments after  attaining  a  chance  success.  This  type 
of  learning  is  the  one  mainly  followed  by  the  less- 
developed  mammals,  but  in  the  apes  the  curve  of 
learning  simple  things  usually  shows  a  sudden  de- 
scent from  the  start.  One  reason  for  her  compara- 
tively slow  progress  in  the  experiments  with  the 
boxes  and  the  bottles  is,  I  suspect,  that  in  her  eager- 

Iness  to  attain  the  desired  end  her  attention  was 
never  strongly  directed  to  the  means  employed. 
When  we  attempt  to  solve  a  puzzle  we  direct  our 
attention  to  the  means  we  employ  and  pass  judg- 
ments upon  them,  but  Lizzie  never  discovered  the 
value  of  paying  attention  to  method.  Her  impul- 
siveness and  activity  stood  in  the  way  of  her  at- 
taining any  results  that  required  a  small  amount  of 
deliberation. 

The  perception  of  very  simple  relations  usually 
escaped  her.  She  never  clearly  perceived  that  a 
hook  could  be  unfastened  by  simply  pulling  it  to 

,  one  side,  that  a  button  would  not  hold  a  door  closed 
when  turned  in   a  certain   position;   she  probably 

'  never  became  clearly  aware  that  when  a  bottle  was 
turned  upside  down  its  contents  would  fall  out.  As 
we  know  these  things,  they  involve  a  certain  pre- 
vision, or  representation  to  ourselves  of  how  cer- 
tain things  might  happen  if  certain  conditions  were 
fulfilled.  But  this  power  was  but  slightly  developed 
in  Lizzie's  mind.     There  are  more  indications  of  it 


The  Mind  of  a  Monkey 


261 


in  Lizzie's  performances  in  pulling  in  the  board  hy 
the  two  nails.  The  quickness  with  which  she  Icarneel 
the  elements  of  the  trick  indicated  that  she  perceived 
the  way  in  which  it  might  he  done  hy  simply  in- 
specting the  situation.  Hut  we  should  be  cautious 
in  our  interpretations,  because  it  was  not  known  how 
near  such  actions  might  have  been  to  her  previous 
experience.  Had  she,  for  instance,  been  used  to 
pulling  in  branches  with  fruit  attached  to  them,  pull-' 
ing  in  the  board  might  have  been  a  particular  ap- 
plication of  some  of  her  previous  activities  for  which 
she  may  have  had  a  strong  instinctive  bent. 

While   it  may   not  be   safe  to   deny  to   Liz/ic   a 
certain   amount  of   prevision  in   her   performances 
with  the  board,  we  should  hardly  be  justified  in  say- 
ing that  they  necessarily  involved  the  drawing  of 
an  explicit  inference.     Should  one  ask  if  Lizzie  were 
able  to  reason,  the  answer  would  have  to  depend  on 
how  reason  were  defined.     That  some  of  her  acts 
are  the  outcome  of  simple  inference,   though  per- 
haps not  explicitly  formulated  in  her  mind,  is  quite- 
probable.     Even  perception,  as  Spencer,  Binct,  and 
others  have  shown,  is  allied  to  inference;  and  Liz- 
zie's behavior  evinces  a  much  closer  approach   to 
the  rational  type  than  does  the  process  of  simple 
perception.     Her  behavior  does  not  indicate  so  high  \ 
a  degree  of  mental  development  as  that  of  several  \ 
other  monkeys  that  have   been   the   subject   of   ex- 
periment.    Whether  her  relative  ineptitude  for  cer- 
tain tasks  is  an  individual  peculiarity  ur  a  trait  char- 


262 


Siiuiifs  in  Juimal  litlunior 


actcristic  of  her  species  cannot  be  stated  with  any 
assurance. 

As  I  have  remarked  in  another  work,  "We  are 
apt  to  overestimate  the  importance  of  the  ability 
to  reason  as  if  it  were  the  chief  thing  of  value  in 
intelligent  behavior.  There  are  other  mental  traits 
which  may  enable  an  animal  to  get  what  it  wants 
better  than  an  increment  of  reasoning  power,  (len- 
cral  activity,  power  of  attention,  interest,  quickness 
of  forming  associations,  delicacy  of  discrimination, 
duration  of  memory,  and  the  ability  tc  form  com- 
plex associations  are  all  of  the  utmost  importance 
in  many  situations  of  an  animal's  life.  .  .  ,  Give 
a  fox  greater  power  of  inferential  thinking,  but  de- 
crease his  alertness,  curiosity,  suspiciousness,  and 
quickness  of  perception,  and  he  might  fall  a  victim 
to  the  hunter  while  his  mind  was  employed  on  some 
other  subject."  Possibly  more  intelligence  of  the 
human  sort  would  have  been  a  positive  drawback 
under  the  conditions  of  Lizzie's  natural  environ- 
ment. 


INDEX 


AlU-n,  B.  M..  188  l'"-'.  I'«l'  'vi'>r  of,  177  If. 

Aimrlm.    hehavior   of,    :»'2.    1.'7,  Cilsiis,  li 

m^j  (')ilnM|il,'i.st>;,     reliction     'if     to 

Ami)hiiiotls,   jihototiixis    in,   .j7.  lijrht,  9C,  0" 

58  *    •'■"■o,  U» 

Andnws.  K.  A..  :>^'J  t  l"'''.  C.  .\i  ,  KW-1G9 

Anonioni-s,  ht-havior  of,  l.'.'»-U7  ("ol<',  L.  Ji  <''5 

Aquinas.  St.  Thomas,  11.  15  Cotiiiuiisiitory    motions,    f>;»-fi«N 

Art-nicola   larvu',  jiliototuxis  in,  84 

5(5^  57  C'ontiiliac,  I',.  H.,  <li',  li> 

Ari.stotU-,  11,  1-M5  C..,Ml."(ls.    SIX    r.n.gnilion    in. 

Bain,  A.,  45,  IM,  134,  1  t(>,  163,  Criitr.  W.,  ^3t,  ;>3,-, 

164  Crayi  ^h,    intrllitfiii.  e    of,     !.•(•, 

Bulanus    larvae,    phototaxis    in,  13<i 

98,  99,  lOJ,  105  Cjtotropisui,  ISO 
Baldwin,  J.  M..  28,  30,  133 
Bancroft,  F.  W.,  89,  107 

Baut-r,  v.,  106  Dtiilinia.  iiiiotol,ixi>  in,  9rt,  10.', 

Bert,  P.,  53  105-108 

Belostoma,    (Uath    feifming    in,  Oaruin,  C'li.,  ij^y^,  IT,  r>\.  lOO. 

202,  209-214  205 

Binet,  A.,  177  Darwin.   E.,   17-19 

Bohn,  G.,  125  Duv.nport,  C.  B.,  113 

Bonjcant.  Father,  16  D.-.th  ftigninc  197  ff. 

Brundin,  M.,  80,  81  DiCandollf,  A.,  53 

Biinst-n-Uoscoe  Law,  89.  90  De    Cet-r,   Ch.,   213 

Buttcrtlies,   orientation   of,  86-  Descartes,  K.,  15,  16,  21,  -'-' 

gg  Dewey,  .J.,  10 

Dice."  I,.    H.,   102,   103.   \<  \   106 

Carpenter,  F.  W.,  93  DifTerential  sensibility,   rule  of 

Carausius,  death  feint,  209,  214,  in  orientation,  82-90 

2iQ  Driesch,   11.,  HI 

36i 


2^4 


In  do 


•X 


l)rirs(i|pliilil,      lll'i-tf       of      illtlllM- 

li^lit  oil.  !i;J,  '.n 

Kiirtli»i<riii,    |ilMi|iitii\is    ill,    ()■>, 

71  T.\,   7'>-77,    1  l:t 
liiii.r,  ().   i; ,  .'X,   !.'.> 
IUi-<-triitiixis,  reversal  of,  107 
l\|iitlieli(il     cells,     lieliinior     of, 

lHt-Ih7 

l''.ii(li'ii(lriiiiii,  effeel  of  |ij:lil   on, 

lluKli'iin,  orienljitiiin  of,  H!» 
l.wald,  W.   I'.,  !»(»,  lOi 

inhre,  ,1.   II.,  Sh,  1!)7,  1!W.  ;,'1.>, 

2H)-i22 
I  listen,  N.,  19i 

licldliT  rriihs,  pliolutaxis  in,  M 
I'ishcs,    piirentai    cure    in,    UO, 
14.) 
reeo(;nitioii  of  s<'x,  .':J(I-.';J1 
rlieutaxis  in,  *il,  (i.j 
I'iske,  J..  46 

I"ly  liirvii',  j)hototHxi.s  in,  74-77 
I'orel,  A.,  1-»1 
Iriinee,  H.  II.,  -2* 
I'rojrs,  sex   recognition   in,    -Ml- 
sJ33 

C.ilen,   1.' 
(Jassendi,  17 
(ieolaxis,  (il 
(Hiltz,  !•'.,  i?31-i>J:{ 
Coodsjieed,   T.  H.,  1 07 
(Jniber,  v.,  53 
Crooni.  T.  T.,  i)9 
(iroos,  K.,  27,  ao 

Ilaeekel.   E..  J8,  177 
Hall,  Vi.  .Stanley.  30 


Il.irjiir,  I',.  II  .  7  I.  7ii,  I'lfi 
1 1  in  I^'1I|,   K.  ( ;  ,   |.,-,,   |i,<i 
lle^'inr.    It.    U'.    IsH 
II'  ||,p|^M|li^^l,  .J.',  ■>».  'Hi 
II..I.)M.iisr.    I.,    r.,   :{;»,    11(1,    Itl, 
Hi 

lloiiiM  s.  .s.  .1.,  ;i  7(i.  H), !»;,  1 11, 
I'.'i  tr..    I  Sit,   iM.-,-ih7,    i<>u, 

.'"1  .'(Wi,    .'(»!». Ml,    2i:t,    .M.'», 

HiiiNon,  W.  II.,  Joii,  J07 

II lime,  I).,   IJO 

Ilyalella,     sex     rt  cinrnition     in, 

Il>ilr;i.  Iiehavior  of,    I.'.-.,  1-J8 
ll>  |<niitisiii   in   animals,  J|  V 

liieiiliatiiin,  orijiin  of.  41,  4.' 
Inhiliitiiin,  i:li,  i:i;i-i;j(i.  i:jn 

in  tropisMis,  1  i:}-l  |ii 
Instinct,  analysis  of,  30,  31.  .11 

ori(;in  of.  2:>,  2ii,  \2J,  1.'3 
Inteilifteiice,       liegiiniings       of, 
l.'O  tr. 

critical  study  of,  33.  34 

•lackson,     II.     II.      1'.,     111.-,,     l()(i 

James.  \V.,  l.'H 

.lenninjfs.  11.  S.,  70,  71.  7(i.  Mf), 

U'().  l-'7.  15«,   I.'jS 
Jensen.   1'.,    Kil 

Kirliy,  W.,  1<»>» 
Kirkpatriek,   K.   A.,  30 

I.ama-ck,  ,1.   B..  .'-.'-.'l.  122 
Laniarckian   factor.  .'H,  .'9,  ItiO- 

I.earninfr.  |irol>lem  of,  13!)  ff. 
I.eccli,  j)liotota.\is   in,   71.   73,  S2 


Index 


261; 


Lriliniti,  Ci.  W..  17 
l.c|iti>pliiiiM,    lii-lia\ior    (if,     l(i7, 

I.rmwyfcs.  twhavior  of.  lH!>-li);J 
l.rUny,  C...    17.    !!•.   Ji 
I..  WIS  (1.  H.,  HI,  li-A 
l.<H>li,  J..  M,  53-.5.>,   ti!t,   77,   7rt. 

HI,  H4,  89,  90.  !»h,   KM,   KW, 

105,  113,   lil,  IBIJ 
I.ofli,  L.,   1K5 
I.uxophylluin,   U'lutviiir  uf,   IJ'>, 

l(i9-174 
I.iililiix'k,  Sir  J.,  M 
I. yon.  K.  P.,  64 

MHlrbranohe.  16 

.Miiiiiiiiiils,    .H«-x    rfcugnition    in, 

235,  240 
Mnssart,  J..   101,  190 
MhsI,  .so.  5ti.  7J,  7t).  84,  89,  99, 

109-111 
McOinnis,  M.  ().,  106 
MoGraw,  K..  84,  85 
Mirhrner,  E.  K.,  105,  106 
Monkey,   intelligence   of,  i'4j  ff. 
Morgan,   C.    Lloyd,   27,   28,   34, 

121,   129.  177 
Morgan,  principle  of,  34,  79,  130 
Morgan,  L.  H.,  207 
Moore,  A.   R.,   105,  107 
Moore,  B.,  109,  109 
Moths,    sex    discrimination    in, 

220-222 

N'cpa,  deatii   feint  in.  209,  210, 

212.  214 
N'erve    cells,    l)ehavior    of,    188, 

189 
Notonecta,  phototaxib  in,  01,  80 


Oltinanns  I".,  99 

OpIMl.  A  ,  |w5 

Orclii^tiii,  pliotoliixis  III,  J7,  H<)- 

M.>.   llHI,   101,  10.'.  105 
Oricntiilion.  .',1,  56-61,  69  ff. 

I'liiii.  relation  to  li'iirniiig,   131- 

1*7,  Ito,  143  ff. 
I'niey.  W..  2<J 
I'liniinirciiini,  l>rlm\ior  of,   156. 

157 
elect rotiixis   of,    107 
Parental  care.  34  ff. 
Parker.  G.  H..  89.  103,  104.  228 
Parinelee.  .M.  P..  30 
Pawlow.  J.    P..    150 
Pauly,  A..  28 
Pearl.  H..  112 
Penrse.  .S.  A..  229,  2:W 
Pigeons,  recognition  of  m-x,  2*.lt, 

235 
Pigment  cells,  behavior  of,  1H2- 

184 
Plunarians,     In-havior    of,     112, 

166-169 
Plato.  12 
Pleasure,    relation    to    learning, 

131-137,  IW,  lU  tf. 
Pliny.  12 
Plutarch,  12 
Porphyry.  12 
Preyer,  W.,  214 
Prototoa,    hehavior    of.   32,    IW. 

169  ff. 

HadI,  K.,  63 

Hanatra,  death  feigning  of,  201, 
■209-211,  213,  214 
phototaxis  in,  59-62,  MO.  !)l.  9.1, 
102,  104,  108 


266 


Index 


l<  indoiii  triovj-mcnts,  KM 

rule  jti  (irii-iitatiiiii,  70-78 
Heasod  in  iiiiiiiial>,  9,  .>.j<)-J(ii 
I{<t\<s.  C.  I).,  .>;j(),  .'HI 
Kijf.TK-ratic.ii       and       Ixhavior. 

um  ff. 
Kciniariis,  S.   II.,  1!).  i>0 
llliccitaxis,  (il,  I,:, 
KliiiiiiMcr,  I,.,   180 
HolM-rtson,  T.    H.,   .>i.',   i\:\ 
Hornatits,  (1.  ,f.,  .'((,  j;,  ,>«,  ,',u, 

"!'.   1.'-'.  .'It 
Itonx,   \V.,   IMO 
Hoycr,  .J.,  (i(i,  (i7 

Sacks,  J.,  ;,.>,   -,:» 
SitlMlllll,   1'.,  .'■;!),  .>14.,    >\Q 
S<\.rin.    II.   C".    and    II.    H,    p., 

.'<lil.   :.'1(),   ;>i.),   .>|;j,  ^)it 
Six   in   mental  evolution,   iM  ff. 

retiijjnilion    of,    -'!!»  ff. 
Slime  molds,  heli.n  ior  of,  l!t;{ 
S|ie!ire,   U'.,  199 
Silencer.    II.,   ^i.    .>.-,.   .>H,   :{|.   .V), 

".I,  11-',  i;j:i,  i:j9.  kw.  i6t 
Spiders,  death  feigninj,'  of,  :»(X), 

-'1.',  .'i:j 
Slahl.    F...  97 

Stenfor,  behavior  of,  \ir,-\21 
Straslmrger.   Iv.   !»(>,   97,  98,   lol 

'I'alorehestia,  deatli   feiffniiiff  of, 
MX    >i)V 
photiitaxi-,  in,  .>7,  91 


'I'enip.rature,    influence   on    Iro 

Jiisins.   94,    lOI-lOS 
Terns,    death    feijrnin^t   of,   2nj 

'Iliijfinota.xis.    lOIMO.j,    n;,,    ih.> 

I  Hi,    l8(i.    189,    .'I,', 
'I'homHsiii.s,  17 
Thorndike,  I'..,  :tj,  1H9-U.',   Ui 

119-1,51 
Torrey.   II.   H.,  S!) 
Toule,  K.   W.,   lot 
I'ri.d  ami    Krror,   l,j,i  ff„  J.vi  ff. 
Iropisius,     relation     of     to     in- 
stinct, :n,  M,  .-,.',  (i.),  (i;j 
reversal  of,  9:i 

\'erworn,  .M.,  !»9,  i\\ 

Voice,     primary      function     of, 

2U->\:\ 
Voltaire,  ti7 
N'olvox,    re/i.tion     to    light,    99, 

107,  109-111,  lU 

Wasniann,  K.,  .'J,  ,>7,   i.>i 

U'lisinann,   A.,  .>8 

Whitman,    ('.    ().,     ^8,    41,    4.?, 

Wilson,   H.    v.,   191 
Wnndt,  W.,  .'8,   \i2 

Yerkes,   H.   M.,  ,i:{,  mt,  l.>9 

/or  Strassen,  II.,  19j 


U  ~ 


